Modifications to parser regarding NAL info decoding.

* Each nalEntry now has a void* to store a pointer to a structure.
* Each nal has an associated nal structure allocated for it.
* Nal info freed on destructor.
* Added comment blocks
* Added arrays to keep track of VPS/SPS/PPS nals.
Added comments
Changes to the hevcstream class.

* Note in nalEntry class whether startcode is 24 or 32bit.
* catch out_of_range condition caused by scanning at the end of file.
* Reset nal_count on Close().
* Added picture_count() and nal_count() to retrieve values.
* Fix display of short dump header.
* Started to implement code to save NAL units.
Changes to nalEntry class.

* Comments for the structures.
* New DUMP_EXTRA flag added to DUMP_FLAGS.
Added -d option to hevcstream application.

* Added -d dump option to main.cpp
* Dump nal vector if -d option passed.