0.9.0 index format is not compatible with the previous index format.

Bugfix

Some Mmap objects were being leaked, and would never get released. (@fulmicoton)

New Features

• Added IndexReader. By default, index is reloaded automatically upon new commits (@fulmicoton)
• Stemming in other language possible (@pentlander)
• Added grouped add and delete operations.
  They are guaranteed to happen together (i.e. they cannot be split by a commit).
  In addition, adds are guaranteed to happen on the same segment. (@elbow-jason)
• Added DateTime field (@barrotsteindev)

Misc improvements

• Indexer memory footprint improved. (VInt comp, inlining the first block. (@fulmicoton)
• Removed most unsafe (@fulmicoton)
• Segments with no docs are deleted earlier (@barrotsteindev)
• Removed INT_STORED and INT_INDEXED. It is now possible to use STORED and INDEXED
  for int fields. (@fulmicoton)