Added a few utility classes from Haiku. To be removed when WebPositive moves
into Haiku. Added new file HashKeys.h which implements commonly used HashKey
classes. Additionally to the ones found in HashMap.h, it has a HashKeyString
class, which wraps a BString and provides the GetHashCode() method.

git-svn-id: http://svn.haiku-os.org/webpositive/webkit/trunk@477 94f232f2-1747-11df-bad5-a5bfde151594

Added a few utility classes from Haiku. To be removed when WebPositive moves
into Haiku. Added new file HashKeys.h which implements commonly used HashKey
classes. Additionally to the ones found in HashMap.h, it has a HashKeyString
class, which wraps a BString and provides the GetHashCode() method.

git-svn-id: http://svn.haiku-os.org/webpositive/webkit/trunk@477 94f232f2-1747-11df-bad5-a5bfde151594