renamed SStage to STest, 'coz that's really what it is
bugfix to allow a const variable to be one-shot set on registration
bugfix for cvar tests
warning messages when attempting to alter const cvars
some extra commenting in the header to make things clearer
bugfix a macro description
removed spurious seperator and blank lines
unit test fixes (wip)
updated cvar tests
test unit test flow (wip)

more unit test tweaking (wip)