v1.2 Write Support!

In this release a lot has changed - and the API was changed dramatically. I apologize if that inconvenienced anyone.

I finally merged in the writer branch after doing some live-fire tests. Worked without a hitch - parties and confetti all around!

Summary of changes: (in case you don't read commit notes)

• New class to write assets ChattelWriter with method PutAssetSync and alias WriteAssetSync.
• Configuration was split into its own class ChattelConfiguration. This was due to happen, just too much logic in there to copy into the new ChattelWriter class.
• Cache disk format changed. You'll want to purge your local cache. You can do that with the new flag documented below, or just by emptying the cache folder.
• Added optional flag to c'tors to allow the purging of the cache on bootup. Some applications might want to clean out the local cache, if they've enabled it, when they start the program - maybe if you're connecting to a different grid and want to make sure you don't get collisions? Also when you upgrade Chattel and there' a change in the cache format - like this release.
• New custom exception classes: AssetException, AssetExistsException which inherits from AssetException, and AssetWriteException which also inherits from AssetException.
• Internal-use-only classes were hidden via the internal keyword.
• Some small bugs squashed and code cleaned up.