Make ESM::Faction skills optional (Fixes #1508)

Also increased size of mSkills array to 7. Some factions with 7 skills can be found in the vanilla CS. The previously "mUnknown" int appears to be the 7th element of the skills array.
Make Bipedal creatures always able to walk and swim (Fixes #1509)

This is necessary since the vanilla CS greys out the walk/swim checkboxes when Bipedal is checked.
Attempt to open companion window if no greetings are found (Bug #1507)
Add items to player inventory upon drag start (Fixes #1507)
Clear MyGUI's clipboard, since we don't want to use it (Fixes #1277)

This would cause pasted text to appear twice, but only when using an SVN version of MyGUI, since 3.2 had a bug where it wouldn't recognize the Ctrl C/V/X keys when using separated key/textinput events.
Fix weapon incorrectly showing when saving and loading with spell equipped
Fix WeaponAnimationTime not working after restoring draw state (when loading save or re-entering a cell - Fixes #1497)
Fix a journal layout bug
Remove terrain limit warning text that no longer applies
Allow following NPCs to fast-travel (Fixes #1501)