[platform][stellaris] Add a full copy of the TI Stellarisware 9453 driver lib

A few modifications were made to the files:
-Removed a huge pile of unused register defs headers from inc/
-Converted all line endings in source files to unix
-Removed some prebuilt libraries
[platform][stellaris] point the headers and implementations to the stellarisware files
[make] fix compile.mk to properly use MODULE_INCLUDES
[platform][stellaris] reformat according to scripts/codestyle
[platform][stellaris] rearrange some headers
[target][stellaris-launchpad] enable debug LEDs
[platform][stellaris] get systick firing properly
[platform][stellaris] make timer implementation much more efficient

Explored using a hardware 64bit counter, but the division to get
back to usec and msec is far more expensive than the ticking
method using systick. Spiff up the current_time() mechanism to
calculate on its own and avoid expensive 64bit divides.
[app][tests] add more tests to clock_tests
[project][stellaris-launchpad-test] add more debug commands