Modification to ButtonController, so that read-only list of widgets is

Modification to ButtonController, so that read-only list of widgets is
not refreshed every time Restore,Apply,Ok,Cancel are pressed. Has the real
advantage that the GUI's can control the widgets more accurately, since the
ButtonController cannot.

Demonstrated with some small change to the Paragraph dialog: enabling the
align buttons is now dependent on the AlignPossible entry in the Layout.

Also apply a small bug fix to getVectorFromString in helper_funcs.C

git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/trunk@2087 a592a061-630c-0410-9148-cb99ea01b6c8