Compiles on OSX 10.9 with Xcode 6.0
Update building.md
Updated a_star.cpp to use tabs instead of spaces
Moved cross platform include for pty into a local header within crossplatform/
Merge branch 'master' into osx_fixes

Conflicts:
	building.md
	cpp/console/tests.cpp
	cpp/pathfinding/a_star.cpp