0.7.0

Changes in this release:

• IndexedGzipFile.__init__ has a new option, drop_handles which causes an IndexedGzipFile to close/re-open the underlying file handle on every access (#5, #6). This has no impact on performance (as measured by the new benchmark script, so is enabled by default.
• New simpler benchmark script.
• Deprecated the fid parameter to IndexedGzipFile.__init__ in favour of fileobj - another change to make IndexedGzipFile more similar to gzip.GzipFile.