Remove a duplicate code for dialog select dir list.

Fix issue when using a page layout file in project folder: eeschema and Pcbnew did not use it, unless using an absolute path.
Now, if the file path is nor absolute, it is seen as relative to the project (which is the expected behavior)
fp lib wizard: when pcbnew id compiled with USE_GITHUB_PLUGIN=OFF, the github plugin option is no more accessible (and the web viewer no more used).

Freeroute dialog: remove freeroute access via java web start, because freeroutecanot be run now via java web start.
freeroute.jarcan be run by Kicad, as long freeroute.jar is found by Kicad (for instance if it is in kicad bin folder)

Minor fixes. Remove unused icon. Add 3 new icons. Change one icon (3 icons are from Konstantin Baranowskiy)

Fix remark 1 in Bug #1393277 (the option "use absolute paths" acts reversed: ticked exports relative paths, unticked exports absolute paths)

- re-worked PNS_LINE_PLACER and PNS_ROUTER classes a bit, removing duplicate class members
- cleaned up Andrew's blind/buried via fixes
- fixed 'custom via width' dialog bug updating the width even when closed/cancelled
- fixed incorrect radius of drawn microvias

* Fix assertions in Eeschema when editing net labels, electronic rules check,
  and plotting.
* Fix assertion when opening PCB calculator.
* Fix assertions in Pcbnew when changing footprints in footprint properties
  dialog and adding or editing text.

Eeschema, Plot dialog: add Plot directory selection. The patch from 1383026@bugs.launchpad.net was widely used.

* Improve VRML export dialog lay out.
* Make the OK button the default action in the export dialog.
* Make 3D model export work correctly and avoid redundant file copies.
* Fix embedded path separators in wrl files on windows.
* Fix absolute model file path creation in wrl files.
* Clean up VRML export code.

* Remove obsolete settings from Doxygen configuration file.
* Fix some Doxygen warnings.
* Add the board edge segment snapping to developers road map.
* Fix some coding style issues in CMakeLists.txt

Pcbnew: fix Bug #1373468 (Non Copper Zones Properties  dialog "Layer selection" empty) (Linux specific)

Minor fixes: specctra export: skip malformed circles (having a radius = 0)  in board outline creation, which can crash 3d-viewer or vrml export.
dialog_fp_lib_table: remember during a session the last open table (global or local).
drawing_tool: fix compil warning
Update demos.

* Set wxGrid tab behavior to leave grid when using the tab key.
* Lots of coding policy fixes.

Ref and Value for footprints: use now the layer color, not a specific color: this is needed by the fact these fields can be on an other layer than silk screen, and therefore must have the corresponding color
Also do not allow copper layers, solder paste and solder mask: put Ref or Value on these layers has no sense, and can create serious issues on the board.

Factored out text ellipsing support to max 15 character (for generating menu items)

Since reference and value are not anymore always on silk changed the label on the corresponding options in the plot dialog
The 'proper Gerber extensions' was renamed in dialog as 'Protel Gerberl extensions': I don't know if it was a typo/misunderstanding or what but the proper extension is gbr; the set of alternative extensions seems to be the one used by Protel/Altium.

- Removed the friends MODULE and FOOTPRINT_EDIT_FRAME from TEXTE_MODULE
  (as in the @todo comment)

- Refactored the Rotate/Flip/Mirror for text in modules into the
  TEXTE_MODULE class itself (members RotateWithModule, FlipWithModule,
  MirrorWithModule)

- New behaviour in coloring text on screen: reference and value still
  take the color from the MOD_TEXT_FR_VISIBLE and MOD_TEXT_BK_VISIBLE
  visibles; other text takes the color of the layer containing it
  (except when hidden, obviously) but still get its visibility
  controlled by those visibles (probably the most intuitive and useful
  behaviour)

- Still need to decide: should text on a layer be hidden when the layer
  is? Probably yes (still to be implemented);

- Some comment fixed and many cast converted to static_cast

Kicad:  more understandable dialog when creating a project from template. Fix also a bug when copying and renaming template files.
Pcbnew: dialog to create new .pretty lib: fix an issue which prevent to open a full disk directory (at least on Windows)

* Refresh canvas when user cancels edits so that the discarded sheet is
  cleared from the schematic.
* Add file name validation to the sheet properties dialog to prevent
  illegal file name characters from being entered into the text control.
* Rename FOOTPRINT_NAME_VALIDATOR to FILE_NAME_CHAR_VALIDATOR for clarity.

Rework on env. variable KISYS3DMOD. Until now, was used in different files using different ways, so no consistency between files.
code cleanup.

  *) When kicad.exe closes a project, close any open KIFACEs so that they cannot
     get disassociated from their true PROJECT.
  *) Allow loading eeschema library editor from kicad.exe
  *) Allow loading pcbnew library editor from kicad.exe
  *) Rename LIB_COMPONENT to LIB_PART.
  *) Add class PART_LIBS, and PART_LIB.
  *) Make PART_LIBS non-global, i.e. PROJECT specific.
  *) Implement "data on demand" for PART_LIBS
  *) Implement "data on demand" for schematic SEARCH_STACK.
  *) Use RSTRINGs to retain eeschema editor's notion of last library and part being edited.
  *) Get rid of library search on every SCH_COMPONENT::Draw() call, instead use
     a weak pointer.
  *) Remove all chdir() calls so projects don't need to be CWD.
  *) Romove APPEND support from OpenProjectFiles().
  *) Make OpenProjectFiles() robust, even for creating new projects.
  *) Load EESCHEMA colors in the KIWAY::OnKiwayStart() rather in window open,
     and save them in the .eeschema config file, not in the project file.
  *) Fix bug with wxDir() while accessing protected dirs in kicad.exe
  *) Consolidate template copying into PROJECT class, not in kicad.exe source.
  *) Generally untangle eeschema, making its libraries not global but rather
     held in the PROJECT.

* Improve footprint text properties layout.
* Use wxStdDialogButtonSizer instead of manually laid out buttons to improve
  platform UI consistency.

Pcbnew: Commit patch (with very minor changes) about SVG file export with the layers ordered from bottom to top. ( bug 1286646 ), from Thiadmer Riemersma.