Removed TiddlyWiki features that are not relevant to Twine

This is a rebased version of the "unwiki" branch from #157.

The tiddlers have various attributes that were useful when TiddlyWiki was actually used as a wiki, but are no longer useful for passage storage in Twine. So I removed them.

Relevant forum discussion: http://twinery.org/forum/index.php/topic,1782.msg4603.html