import/export automated testing using CMake's CTest

Will need to write full docs on this on the wiki.
basic info.
- 21 tests, OBJ/3DS/X3D/FBX, 3 tests per format import export. STL, PLY, BVH are TODO.
- uses files in ../lib/tests (checkout separate)
- run with CMake Makefiles "make test" or "ctest"
- currently checks against basic MD5 hash on scene import and file MD5 hash on export (realize this wont work predictably on binary formats *TODO*).
- currently uses a generic script for all tests with arguments to specify command to run, expected output, testing method, files to check against etc.

Has already proved useful, found a number of bugs in import export and some in blender too.

CMakeLists.txt

@@ -50,6 +50,8 @@ cmake_minimum_required(VERSION 2.6)
 
 project(Blender)
 
+enable_testing()
+
 #-----------------------------------------------------------------------------
 # Redirect output files