Introduce cmake (min 2.8.12) to StepMania.

tl-dr: view the Build directory to see.

This is intended to replace the project files that we presently maintain
so that only a single set is needed instead of multiples.

The following setups were used for testing:

* Windows 8 and Visual Studio 2013 Desktop Express
* Windows 7 and Visual Studio 2012
* Mac OS X Mavericks and Xcode
* Ubuntu and makefiles
* Fedora 21 and makefiles

All three operating systems can generate projects, compile, link, and
run. Windows and Mac OS X users will find their compiled binary in the
same location as before, but Linux users will be surprised: it goes
straight into the root directory, along with a symlinked GtkModules.so
as appropriate. There is no more need for a manual symlinking step.

Known issues:

* At this time, MinGW likely does not work. Extra time will be needed.
* The WITH_JPEG option may go away, and we'll just always require it.
* Some linux libraries can use the system equivalents, but that is not up yet.

For more information, check out the Build directory.

.gitignore

@@ -2,6 +2,20 @@
 *.o
 *.obj
 
+# CMake Files/Directories
+CMakeFiles/
+CMakeCache.txt
+CMakeScripts/
+cmake_install.cmake
+# The following are generated from CMake, and thus should be stopped.
+Build/*
+Build/*/*
+Debug/
+Release/
+Contents/
+verdata.*
+StepMania-debug
+
 # Text Editor Based Items
 ___*
 *~
@@ -49,6 +63,7 @@ lib*_link.a
 *.suo
 *.exp
 *.ilk
+*.map
 
 # Windows General Files
 Thumbs.db
@@ -73,6 +88,13 @@ src/config.h
 src/config.h.in
 src/stamp-h1
 GtkModule.so
+StepMania
+
+# Version control specific.
+*.BACKUP.*
+*.BASE.*
+*.LOCAL.*
+*.REMOTE.*
 
 # StepMania Specific
 *.smzip
@@ -147,3 +169,4 @@ BuildLog.htm
 *.swp
 *.pc
 *.d
+