Add more extent tree functions
Add red-black tree library code
Move NVFile and NVNode definition to fileops_bankshot2.h
header files Fix
Update offset and count in find_extent
Store lock_id in NVNode
Acquire node write lock for add_extent
Add extent in do_pwrite
copy_to_cache implementation and Makefile fix
Do not double free key since key is freed in RBDelete
cache_length fix. Also for cache file, always open with O_RDWR.
Remove unused variables