[FIX} div.diffbody (in wiki diff views) needs to specify a text color as well as background color to prevent bad contrast especially in dark-background themes.

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/13.x@52177 b456876b-0849-0410-b77d-98878d47e9d5
[FIX} In wiki diff views, td.diffadded and td.diffdeleted don't need max-width values now that the table is responsive (i.e., can have a scrollable width wider than the column).

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/13.x@52178 b456876b-0849-0410-b77d-98878d47e9d5
[FIX]Improve r52160: Remove non-default button class for navigational buttons in the screens under User Preferences (and clear also class btn-wraning for "Empty trash" in tasks just in case someone disliked that).

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/13.x@52179 b456876b-0849-0410-b77d-98878d47e9d5
[FIX]Improve r52161: Remove non-default button class for navigational buttons in Calendars

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/13.x@52180 b456876b-0849-0410-b77d-98878d47e9d5