Pcbnew - plot dialog: fix Bug #1417435 (Gerber(and some others)  plot mode is fixed as”sketch” instead of "filled" )

Dialogs edit footprint in module editor and edit footprint in board editor: add button to edit the selected 3D shape filename.
Dialog edit component in library editor: add button to edit the selected footprint filter.

Dialogs edit footprint in module editor and edit footprint in board editor: add button to edit the selected 3D shape filename.
Dialog edit component in library editor: add button to edit the selected footprint filter.

Pcbnew: simplify draw code in  default canvas and plot functions by removing the plot LINE option, which is not existing in all plotters, not existing in opengl/cairo canvas, and not usefull in default canvas.

ModEdit: add a settings menu option(and the corresponding dialog) to set default values used when creating a footprint or add graphic items to a footprint being edited.
These settings are now not common to the board editor, because the footprint editor can be run outside the board editor.
download_boost.cmake: ignore  .htm* files when installing boost. They are not used, and often have a very very long (and stupid) name which sometimes creates issues.

Class BOARD: Rename an overloaded method named SetLayer with the better name SetLayerDescr, and comment it. It also remove some warnings when compiled with option -Woverloaded-virtual

* Fix -Woverloaded-virtual warning in DIALOG_LIB_NEW_COMPONENT class
  definition.
* Make EDA_ITEM::Matches( const wxString& wxFindReplaceData& ) protected
  since it's a helper function that should only be called by derived objects.

Footprint Editor: New footprint creation: change defaults for ref and value texts: now Ref text is REF** and Value text  is the footprint name. Also Value is put on fab layer (front)
muonde.cpp: cleanup this very old code, and fix not working code.

* Check to see if image handler is already initialized to prevent warning
  on debug builds.
* Change LIB_PART destructor message output to use wxLogDebug for debugging
  on windows builds.
* Minor code cleaning and coding policy fixes.

Fix minor aesthetic issues in dialogs (these minor issues (overlapping widgets)  exit only with some Windows managers like KDE)

Pcbnew: fix Bug #1413701 (Segfault on highlight "unconnected" net 0 in Pcbnew ). Also, remove now useless code and other very minor fixes.

Pcbnew: fix issues and potential issues when reading board files and mainly old board files, and enhance the DRC tests and Delete Single Pad Net option when reading a netlist:
* Delete Single Pad Net option does not delete the net if a zone use this net (i.e. is attached to this pad).
* pcb_parser accept now negative netcodes in zones (can happen with old files, which previously could crash Pcbnew)
* pcb_parser accept now files with incorrect or missing net count  (can happen with old files, which previously could crash Pcbnew)
* if a zone has a non-existent net name it now keep this net name, and DRC detect it (previously, the net name was lost, and the DRC did not tected this issue).
* Drc test: now detect a "dead" net, i.e. a net with 0 pads, but still used by a zone. It happens easily after a schematic modification, when a net disappears or is renamed.

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.

Pcbnew, layers manager: Fix an annoying bug I added in rev 5359, in Render options: in Board editor many render options were not displayed (similar fp editor mode).
Now fixed.

Pcbnew: Fix potential bug in DRAG_SEGM_PICKER (a variable type bool was used as int. type is now int). Minor code cleanup.

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.

Fixes issues with IDF file I/O on Windows (the famous 'ascii vs. binary' issue) and the reported problem of partial paths when KISYS3DMOD is specified.