lib_dxf: Update to version 0.5.13 (previous: 0.5.11) due to a bug (memory leak) fixed in 0.5.13, which has also more comments, and try to fix most of coverity warnings (not initialized class members).
These members are now initialized, which also fix some other more serious coverity issues.

Pcbnew: fix  Bug #1422093 (pcbnew crashes after editing a footprint cominng from the board  with the fp editor and saving it on a librray and trying to load it to the board)
Some other very minor fixes.

* Fix resource leak in idf_parser.cpp
* Fix logically dead code in idf_parser.cpp
* Fix use after free bug in idf_parser.cpp
* Fix unitialized scalar value in idf_parser.cpp
* Fix logically dead code in idf_outlines.cpp
* Fix unitialized scalar value in idf_outlines.cpp
* Fix invalid iterator in idf_common.cpp
* Fix unitialized scalar value in vrml_layer.cpp

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.

* Compile all binaries into a single application bundle.
* Use CMake BundleUtilities to make application bundle relocatable.
* Restructure build output to directly create an image file.
* Fix default search paths.
* Set KIGITHUB environment variable.
* Added patch to fix wxWidgets so names for OSX.

3d viewer: fix a (minor) bug when run from cvpcb or modedit: the footprint is now centered on Z axis
Better setup for lights, which gives a better rendering

.kicad_mod files: always save the "last edited date" because only the footprint editor changes this parameter. Usefull to know if/when a footprint was actually modified.
Also fix a minor issue in footprint editor which always set the "modified" flag even when no change was made.

Fix minor bug in eeschema (opening a relative path does not work) (patch from HennerZeller).