Save document file when creating new component library from component in library editor. (fixes lp:1351952)

* Remove redundant number from unit context menu.
* Use letters instead of numbers in component edit dialog.

Pcbnew: fix Bug #1404191 (Zone filling fails when a zone inside having the same net and a highter priority exists, which is allowed to manage different fill parameters )

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.

Road map: Gerber X2 file function extension marked done in Pcbnew and Gerbview

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

* Make patches/wxwidgets-3.0.2_macosx_yosemite.patch usable.  There were
  complaints here before that the patch does not work because it is a
  "metapatch" that tries to patch another patch (which is not in the tree
  and therefore fails). With this change, it becomes a normal patch again,
  that can be applied to the wxWidgets source tree as described in
  Documentation/compiling/mac-osx.txt.
* Make scripts/library-repos-install.sh compatible with OSX: This involves
  checking for the correct option to enable extended regular expressions in
  sed during detect_pretty_repos, as the script uses "-r", which is only
  available in GNU sed. The sed shipped with Mac OSX is an older BSD descendant
  sed which needs "-E". This change has been tested to work on Mac OSX 10.10.1
  and on an up-to-date Arch Linux.  I also changed the error message during
  --install-prerequisites to inform users without apt-get or yum which programs
  need to be installed to use the script.
* Add the execute flag to scripts/osx_build_wx.sh: At the moment, after
  fetching the source with bzr, one has to chmod the file by hand. This
  change change ensures consistency between the script and the build docs
  for OSX, which assumes the script to be executable.

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.

BOM dialog: remove a not very useful button, and merge its function with an other (not perfect, need more work)
Add message box to show info added in BOM python scripts (See scripts/bom-in-python/README-bom.txt about this info)

Pcbnew, export Solder masks in Gerber Format: fix not working export when the solder mask minimal width is not 0 (the exported shapes were the same as if the vule = 0) with boost version >= 1.56
This is due to the fact the boost::pylygon function resize ( a inflate/deflate function) used for calculations does not work with boost version >= 1.56.
Use Clipper  inflate/deflate function instead. It is faster and works fine.

Modify usage of Inflate/deflate polygon in zone calculations, in order to be compatible with boost::polygon >= 1.56
 Inflate/deflate polygons does not work very well (neither with  boost::polygon >= 1.56 nor with Clipper) for polygons which have holes linked by overlapping segments
(i.e. polygons with holes which can be drawn, because they are see as only one polygon)
Some code cleanup.

Modify usage of Inflate/deflate polygon in zone calculations, in order to be compatible with boost::polygon >= 1.56
Some code cleanup.

* Make defintion of OSX build target a requirement.
* Update OSX build documenation to reflect build changes.
* Update OSX build script to reflect build changes.

Grebview: add info in layer manager for Excellon drill filles, similar to X2 file function info in X2 gerber files.

Eeschema: Netlist generator: remove option to generate the fully outdated old netlist file format (based on a very old Orcad netlist format)
Only the new (S expression) better netlist file format is now used.

Gerbview: Add support for recent File Format Attribute metadata, both for X2 Gerber file format and X1 (R274X) format.
Pcbnew already uses this attribute when creating Gerber files.
Because Gerber files using this attribute identify the board layers stackup, Gerbview (if this attribute is defined) can sort gerber images stach up like the board.
(in layer manager, just right click to access to the sort menu)