PIVOT-696 (part): More work with TAB characters in TextArea.

Add a style "acceptsTab" that changes the behavior of TAB and Ctrl-TAB
(actually reversing them).  The default (false) means Ctrl-TAB inserts
spaces, while TAB shifts focus to next component.  Setting the style
true means TAB does the insert while Ctrl-TAB shifts focus.  The latter
is more in line with other applications.

This is a copy (without merge) of revision 1445449 from branches/2.0.x
to trunk.


git-svn-id: https://svn.apache.org/repos/asf/pivot/trunk@1445470 13f79535-47bb-0310-9956-ffa450edef68