Added additional documentation to TBSite.h.

Also re-wrapped all the old doc comments and one longer method to stay within an 80-character guideline.
Removed a now-unnecessary block typedef.
Removed an unused property from TBPage.h.
Removed an unnecessary forward declaration from TBPage.
Did a bunch of refactoring in TBPage.m.
Added documentation comments to TBPage.h.
Refactored, improved, and documented the TBAsset class.
Merge branch 'master' into editor