Tracker Settings: Use BLayoutBuilder template and refactor

... instead of using the less flexable BGroupLayoutBuilder.

* Reduce Group levels used by eliminating the uneeded top
  level group.
* Use font relative spacing units in a few places instead of
  hard coding 20 pixels.
* By using the layout builder template I can use the single
  parameter version of SetInsets().
Tracker Settings: Re-factor includes

* Remove includes from header and use bare class definitions instead
* Add the includes from the header to the cpp file
* Remove Alert.h include from cpp file, not used.
* Remove TextControl.h include from header, not used.
* Add Point.h include to cpp file, we do use that.
* Reorder includes according to style guidelines
Tracker Settings: Style fixes

* Add spaces around {}'s
* Add 2 blank lines between class declarations in header
Tracker Settings: Put color control a group and add indents

* Also don't set the initial position since the layout kit takes
  care of that for us now.
* Remove the no longer used spacing constants.