Started building the framework to enable the use of different coding schemes in the group analysis model builder.
Assorted GUI fixes and improvements; resolution of several Github issues.
Changed some GUI defaults.
Updated the cpac_run.py script.
Some changes in skullstripping code and GPA.
Fully implemented Treatment coding in the group analysis model builder, at least for most standard models; some expansion may be necessary for when people want to get really creative.
Started changes to output SCA correlations as 4D files.
Merge branch '0.3.8_development' into 0.3.7_func-t1_mod

Conflicts:
	CPAC/__init__.py
Changed the transform ordering for the warp applications.