Changes to bitbuffer to support rbsp with emulation_prevention_three_byte...

* Remove all 0x000003 sequences from a NAL and return a new bitbuffer.
* Use 64bit int as bit position when creating bit iterator.
* Added _DEBUG flag to debug build.
Changes to bitstream_test bench...

* Use PREPROC to enable/disable each test case.
* Test bit iterator ue(v) function.
* Add bitbuffer library as a dependancy.
Changes to hevcstream class.

* Seperate passes for finding startcodes and parsing NAL headers.
Add hevcstream project to workspace.