Thumb format/style updates + More reorganizing

* Made the thumbnail formatting skip thumbnails that are already done by testing for the existence of the "bbb-thumb-link" class.
* Made some more style rules a bit more specific by using the "bbb-thumb-link" class and fixed a slight style priority issue in the comments section.
* Grouped some more functions into the "post functions" and grouped together some functions as "thumbnail functions".
* Stored the location regex in a variable and started using it in place of the separate regex declarations.
* Modified the ddl function so that it can handle the fixing of hidden post links itself and decided that ugoira ddl links should point to their webm versions (debatable?).