Eeschema: fix a minor bug and enhances SCH_MARHER::Matches function (  partial use of  0005-SCH_MARKER-fix-a-Woverloaded-virtual.patch, from <fatzer2@gmail.com> ) and other very minor fix.

Very minor fixes: add missing const return type to some GetBoundingBox() declarations. Change few functions names to better names in some places (like GetName() to GetPinName() )

Minor and very minors fixes: move -DKICAD_USE_WEBKIT definition to the main CMakeLists.txt. Remove duplicate semi-colon at end of some lines.

* if the current select plugin is the github plugin, one can select some of these libraries and add them to the table
* if the current select plugin is the kicad plugin, one can select some of these libraries and download them to make alocal copy.
  They can added to the table after they are downloaded.

Add hight contrast option in Modedit. In hight contrast mode, solder masks and solder paste are shown.
this option was possible only by modifying the way display options are managed.
before these changes, display options were a global DISPLAY_OPTIONS class instance.
Now each EDA_DRAW_FRAME(and derivated classes)  includes its own DISPLAY_OPTIONS class instance.
As a consequence, some duplicate display option variables in these classes have been removed, because there were just duplicate variables of the  DISPLAY_OPTIONS class instance.

Modedit: now shows a specific layers manager, which allows user to select the technical layer which is used when adding a new graphic text or outline to the current footprint.
Please, note the layer manager was already available in GAL mode, but is was the same as tne board editor, which is not good.
Now:
- In default mode or GAL mode, the look is the same.
- Only suitable technical layers (i.e. paired layers) are selectable from the layers manager (for special purposes, some other layers can be used, via the graphic items properties dialog)

* With fixes from Adam Wolf.

Page layout selection: fix Bug #1405972, and add minor enhancement in page layout selection dialog (the new layout is shown after selection).
When the filename is not absolute, the page layout file is now searched first in project folder, and then in kicad template folder, if not found in project.

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).

Allows use of modifier shift key with letters A ... Z  in hot keys (including hot key editor). Thanks to John Bird, who helped me with his patch.

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

Looked like a minor issue, but was due to a more serious bug, when using 2 different DSN_LEXERS which were not synchronized.
The fix is not perfect, but unfortunately, the parser used to read the PCB_PLOT_PARAMS in .kicad_pcb files is also used in legacy board file reader.
Therefore it is better than write 2 parser functions, one for legacy files, the other for the .kicad_pcb files, which make the same thing.

Try to fix an issue on Ubuntu/Unity for some dialogs which are not displayed. For most, adding GetSizer()->Fit( this ) in dialog constructor fix the issue, but at least one dialog still is not displayed.

geometry: IsSolid() and Move() methods, segment overlap detection, some improvements in SHAPE_LINE_CHAIN class.

Polyline.h: remove useless class CRect. Use the more powerful EDA_RECT instead. Clean and remove duplicate code.

Fix many doxygen warnings (due to missing info, old comments, typo ...) when building the doxygen doc.

Pcbnew: Console python: use a wxMiniFrame to show the console and remove the management by a EDA_PANEINFO, which was not the right way to manage this console.

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

Python scripting: make UTF8 class accessible by python scripts. Add python method GetChars() to UTF8 class to get its char buffer.
See scripts/test_kicad_plugin.py for example.

* 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.

* Many path related fixes.
* Fix execution of external applications.
* Update mac-osx.txt.
* Add top-level links for standalone applications inside OSX bundle.
* Fix document icons for Eeschema and pl_editor.
* Create individual bundles for standalone applications inside the main application bundle.
* Add usual 'site-packages' to python path in OSX bundle.
* Fix name of OSX bundle plugin folder.

Rename "Switch highcontrast" to "Toggle High Contrast".
Eliminate most of the abbreviated hotkey titles.
Doxygenize dialog_hotkeys_editor.h and add missing license block.
Display <unassigned> if key code is 0 (NULL).

Refactor hotkey editor to use tab control instead of one giant list.
Each tab is a separate hotkey section.
Modify EDA_HOTKEY_CONFIG to change the m_Comment member to m_Title for a new purpose.
We want a pretty title in the hotkey editor. We use m_Title for the key export comment which
still conveys the purpose just as easily.
Refactored usage of wxGrid into wxListCtrl which allows capturing navigation characters
and also works better (single selection is built in).
Add hotkey overwrite prompts that are paired with "Common" section. It will check if a hotkey
overlaps with the proper sections. i.e. Common with the all other sections; or Section 1 with just Common.
Right-click menu removed due to wxListCtrl being able to catch the special keys properly.

Libview and Modview: fix issues relative to hotkeys (hardcoded keys instead of user defined keys) and not working tools and popup menus.
Fix also some minor coding style issues.

Add FILE_NAME_WITH_PATH_CHAR_VALIDATOR, a custom wxValidator which allows file names with paths, in schematic sheet editor
( FILE_NAME_CHAR_VALIDATOR previously used in this dialog does not allow chars used in path names, like / and on Windows \ and : )