Version 0.5 released

Sat Oct 21 13:47:47 2006 Google Inc. <opensource@google.com>

* sparsehash: version 0.5 release
* Support uint16_t (SunOS) in addition to u_int16_t (BSD) (csilvers)
* Get rid of UNDERSTANDS_ITERATOR_TAGS; everyone understands (csilvers)
* Test that empty-key and deleted-key differ (rbayardo)
* Fix example docs: strcmp needs to test for NULL (csilvers)