add comments in BgzfInflate and BgzfInflateBase classes
refactor BgzfInflate class and add method which explicitely returns the EOF flag of the underlying stream in case of an empty BGZF block
move BgzfInflateInfo to its own file
refactor parallel bgzf I/O
- add BgzfStreamWrapper class
- improve eof handling in serial bgzf decoding
  - ignore in file empty/eof blocks
  - throw exception if there is no eof block at the end of a stream