make new subpackages under src/test/../headless

it was getting too confusing having all of it just mixed together
minor cleanup
remove commented-out code
split a test off into its own file
further splitting up of test/..../headless.lang
disperse headless.misc.TestCompiler to the winds

relocate tests to lower packages or to headless.lang when
possible. some redundant tests eliminated.
cleanup in headless.lang.Parser
cleanup/refactor in headless.lang
further fiddling with headless.lang
Merge remote-tracking branch 'origin/headless' into tortoise