Admin Form Cleanup

1. Move general settings into an expanded fieldset for consistency - keeps the settings together after sorting or when other modules attempt to affect sort order using weights
2. Hide advanced_help when the module is not enabled - I left the version's (broken) CVS keywords in place for lack of a recommended alternative
3. Move CrossRef fieldset to the crossref module - more appropriate location, and it preps for CrossRef configs that I'm look at adding
4. Fix the 'absolute' key typo - just a typo
5. Add a weight to the buttons element so that they stay at the very bottom of the form

This is mostly cosmetic and minor, but it gets things organized so that it plays nicer with other modules that hook into the form. Patch coming momentarily.