Added a "modified" signal to TextFormatButtons

As i'm not sure that the edits done to the text feild by TextFormatButtons, i've added a signal that will fire if anything in it is clicked as if to say "the formatting has been changed"

Refs #7865
Axis tab now applys, continuing work on scale tab

Added the modified and valid flags to both classes in order to streamline applying.

AxisAxisDetials is now pessing chages to the graph, but the section in AxesDialog is not complete and the code there is just for testing.

Refs #7865
Discovered Grid tab had the same problem

Added a new class GridDetails, as the Grid tab has a similair problem to the Scale and Axis tabs. So i plan to solve it in the same way.

Refs #7865