Add fix from https://github.com/pavouk/lgi/issues/66

That allows instantiating foreign objects properly.
Make sure filename is included for moonscript loading errors
Removed old bytecode before compiling new

Stale bytecode that lingers after removing a file can cause consternation.
ifdef the deprecated g_type_init
Go all FFI for the Scintilla integration

Using both the C api and the FFI causes problems, since we're
getting callbacks from the C api during a FFI call which is illegal.

This has actually worked out very well in practice regardless, since
we've used only one thread, experimenting with coroutines exposed
this right away (SEGV).