Add/fix the Language: header in PO files.
Add all Retina sizes to OS X app and doc icons.
Update wxWidgets to fix warnings.
Update Lucene++ to fix warnings.
Update Sparkle to fix warnings.
Use consistent visibility-related settings in Xcode.

Fix linkage warnings related to visibility by using the same visibility
settings everywhere.  Enable visibility in projects that have code-level
support for it (Boost, Lucene++).
Xcode: silence some warnings in wx's 3rd party code.
Fix or silence misc Boost warnings.
Xcode: Silence warnings in CLI deps builds.
VS2013: Fix ICU warnings.
Silence stupid VS2013 warnings in Poedit itself.

Silence two things: STL "insecure" warnings (bogus) and the
super-annoying "conversion to bool" 4800 one.
Fix legit warnings in Poedit code.
Fix conflicts between expat.vcxproj and zlib.vcxproj.
Fix warnings in REKit.

Switch to own fork to be able to use my fixes.
Merge branch 'fix-all-warnings' into stable

Fix warnings under Xcode 5 and VS 2013 in Poedit and its dependencies, so that
the build is clean.
Update wxWidgets.

Fixing deletion of window during mouse down handler.