Add "Planet plant" music by jobromedia.

Source: http://secretmaryo.org/phpBB3/viewtopic.php?f=11&t=5053#p31012
Delete all test levels from the official level collection.

As per @sauer2’s suggestion in issue #59.
Fix thromp velocity not being saved
Fix documentation of Std::Enable
Add Convert_Path_Separators() override for boost::filesystem::path
Fix invalid path handling in cStatic.

Invalid UTF-16 conversion for Windows.
Remove outdated compilation line from README
Don’t save backslashes in .smclvl files on Windows. Fixes #104.

They can’t be opened on *nix otherwise.
Add revised versions of @sauer2’s levels. See ticket #59.
Renamed game data directories.

In order to have consistend naming for user and game data directorys,
the game data directories for "world" and "campaign" have been renamed
to "worlds" and "campaigns"
Merge branch 'fix-datadirs' of git://github.com/brianvanderburg2/SMC into devel
Fix FallingGoldpiece classname
Add Ball to mruby scripting interface
Fix inheritance chain of ParticleEmitter in mruby scripting interface
Fix editor not allowing negative values for particle emitter gravity.
Allow UIDS::[] method to take *rest argument.

This makes it possible to call it with a list of UIDs now instead
of having to use a range or hackish mapping. Just do

  sprite_ary = UIDS[10, 20, 233]

and you’re done. The previous call sequences are still possible,
of course.

  sprite     = UIDS[14]
  sprite_ary = UIDS[10..20]
Add basic win32 installer using CPack and NSIS (#113).

This is not finished yet.
Add more detailed CPack+NSIS configuration. (#113)
Add icon to windows executable. Closes #113.
Update README with win32 setup installer build instructions