To fix SANS system tests

Changed parameter types to be ArrayProperty<double> where possible and modified things
for const correctness and pass by reference when possible.

Move normalization code inside its own if statement to prepare optional normalization flag. This refs #4303

It takes about 10 seconds the first time, then 2 seconds each other time. This compares to 21 seconds each time before

6 seconds -> 1 second to calculate the assemblies size in unwrapped view.

Also re-enable workspace locking which I accidentally left disabled

This won't make much of a difference unless you do lots of fits.

in MatrixWorkspace::getDetectorIDToWorkspaceIndexVector(), which is called in the instrument view

1.6 seconds->unmeasurably fast.

 * Creating new color selection widget.
 * Adding new widget to main window layout.
 * Rename color selection widget pointer.
 * Switching to in-program color selection widget.
 * Removing color options dialog code from main program.
 * Removing color options dialog files.

16.6 seconds -> 1 msec, nice :)

Also added further protection for pruning against pruning empty
directories.