add better handling for `readonly` to prevent bugs from `const`-ifying the return value of a member variable (e.g., unexpected copy semantics)
add more tests and add a few more handlers for new readonly type
fix simple_usertype_metatable's handling of newindex and index when not at the top level
More documentation on how things work.
Once more at a 'feature-complete' state. Continue to work on #116.
Add testcase to ensure #108 is fixed. Then, prep release.
Closes#111 - fixed
Closes#110 - need to test exactly how much extra speed was gained
Closes#108 - seems to be fixed, albeit std::mutex is a butt on VC++