fix toggle header/footer logic and make it so it will really "hide" (override !important styles).
Revert "fix toggle header/footer logic and make it so it will really "hide" (override !important styles)."

This reverts commit eb9c52474771b92e3d9e5be5389f4044f80e1163.
Fix custom title and back button text being overwritten when panels transition.
API doc bug fixes.
close #282

fix $.ui.showMask CSS rules
Merge remote-tracking branch 'upstream/2.0' into v2