Depend on doctest

otherwise "make test" will fail
identifiers can contain underscores
convert simple expressions from ObjC to Java
test fist: convert hello.m

The test currently fails, but this is the first realistic target:
recognizable ObjC expressions in a file and convert them to Java,
leaving everything else intact.
Skip unrecognized characters
fail if 'cabal build' does
demo: convert hello.m
recognize short literals last

otherwise the fragment might end sooner than expected
Update README to reflect progress
Rename executable to match README
fix 'new Hello()' syntax