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