Simpler and more successful local collection (and `using`).
Reorganize stuff into 'mains' subdirectory.  Fix microtamsin.

--HG--
rename : eg/tamsin-analyzer-driver.tamsin => mains/analyzer.tamsin
rename : eg/tamsin-compiler.tamsin => mains/compiler.tamsin
rename : eg/tamsin-desugarer-driver.tamsin => mains/desugarer.tamsin
rename : eg/tamsin-micro-interpreter.tamsin => mains/micro-tamsin.tamsin
rename : eg/tamsin-parser-driver.tamsin => mains/parser.tamsin
rename : eg/tamsin-scanner-driver.tamsin => mains/scanner.tamsin
rename : eg/tamsin-parser.tamsin => mains/tamsin-grammar.tamsin
Get scanner test to pass again.
Clean up test suite a bit.
Clean up test script even more: -f files, interpreted/compiled.