Enable silent start of wx

Add {silent_start, boolean()} option to wx:new/1 in order to be able
to suppress error messages during startup of wx.
Merge branch 'maint'
wx: Build targets to platform subdirs

And add code so wx can be run from src tree during development.
Prepare OTP files for Unicode as default encoding
wx: Fix xml-parsing with new doxygen version
wx: Fix code generation bugs

Removed defines that is void, i.e.
-defined(FOO, ?NEVER_DEFINED_VALUE).

Also removed wxSTC:sendMsg/[2|3]
which was wrong before and breaks code generation with new doxygen.
wx: Re-generated code

Generated code with previous commit.
wx: Ifdef changed/removed functionality in wxWidgets-2.9.x
wx: Fixes more changed/removed functionality in 2.9
wx: Deprecate functions not available in wxWidgets-2.9

Prepare to remove functionality which is not available in coming
wxWidgets versions.
wx: Modify tests so they work on wxWidgets-2.9

Things have changed in 2.9 modify tests so they are still valid for
both 2.8 and 2.9 branches, so far only tested on linux.
wx: Update examples so they work with both wxWidgets 2.8 and 2.9
wx: Include correct m4 file in 2.9

The older m4 file will not work with a 2.9 release, so
include the correct one in 2.9
wx: Fix int to enum

In 2.9 several functions takes enum's instead of int as arguments,
remove dirty -fpermissive fix and fix it correctly instead.
wx: Fix changed getfunctions

wx-2.9 have changed some functions from returning references to objects to
returning objects instead
wx: Remove unnecessary casts
wx: Fix loading icons and cursors in Windows

wxWidgets looked in the wrong executable after icons and cursors, stole
wxLua's solution.

Also finds wx-2.9 on windows
wx: Fix the demo

Changing demo, didn't close the previous choosen demo, which
looked really bad on Windows.
wx: Allow 64 bits compilation on mac, requires wxWidgets-2.9

Testing using wxWidgets-2.9 on mac
wx: Fix demo and tests

Added debugging and workarounds for wx-2.9 on Mac