* Filled in some missing/out-of-date documentation, mainly in DG_Gallery
* Modified DG_Gallery to [get/set]Options through DocumentGallery::[get/set]Options, the way other classes handle this
* Migrated demur's Thumbnail table into the Settings API format (incomplete)
  + Still need to:
     - modify submit logic to look something like what is described here: stackoverflow.com/a/11908673/866618
     - remove extra buttons
     - style submit button on thumbnail tab to look like the buttons being removed
     - modify DG_Admin::validateThumbnailSettings() to handle what was previously being done through DG_Admin::multipleDeletion()
     - ensure that DG_Admin::validateThumbnailSettings() returns a valid copy of DG options, with the propper thumbnail ids removed from the thumber branch of the options
     - ensure that DG_Admin::validateThumbnailSettings() does NOT write to the DG options array since this will be handled through the Settings API (make sure physical files are deleted, however)
     - anything else I haven't throught of...

git-svn-id: https://plugins.svn.wordpress.org/document-gallery/trunk@967170 b8457f37-d9ea-0310-8a92-e5e31aec5664