Unit tests

[pgruenbacher]

the MACRO bs_add_test is added. it could be cleaned up but it works for now. it's more up to marko to decide.

make test and ctest should now work when in the Build dir. enable_testing needs to be at root dir. octree

there's still an unhappy lack of testing verbosity but I guess that's a future implementation effort.

/usr/local/bin/ctest --force-new-ctest-process 
Test project /home/pgruenbacher/build/bsframework/bsfMaster/Build
    Start 1: UtilityTests
1/3 Test #1: UtilityTests .....................   Passed    0.52 sec
    Start 2: CoreTests
2/3 Test #2: CoreTests ........................   Passed    0.52 sec
    Start 3: RenderBeastTests
3/3 Test #3: RenderBeastTests .................   Passed    0.52 sec

[BearishSun]

Thanks for making the changes, I made some notes but in general it looks good.