Bsdiff4

-------------------
* fixed file_patch when src_path and dst_path are the same file
* add file_patch_inplace()

-------------------
* while performing the diff, we are now releasing the GIL while performing
nested for loop

-------------------
* add Python 3 support
* improve documentation

-------------------
* add example which implements a slow pure Python patch function
* using cStringIO (instead of StringIO) in format module

-------------------
initial release