vm: Fix a crash when trying tuple assignment.

o_set_item thought that a tuple was implemented like a hash. An easy fix, but
rather embarrassing. :(

I added a small test to test/pass/sanity.ly because this really should be
tested for!
vm: Don't pass vm_regs to build list/tuple.

Have them use vm->vm_regs, like everything else does. It's simpler that way.
Merge common binding in mod_lily and vm into lily_bind.{c,h}

I should have done this when I was making exceptions, instead of copy+pasting
big chunks of code from mod_lily.c. I also changed the functions that were
put in common space to take a symtab (no more making a signature to pass it!)
This means that each bind function has to do a symtab lookup, but that's okay.
vm: Reorganize functions, comment them, and less exporting.

I noticed that quite a few functions weren't marked as static properly, so I
did that as well. No change in functionality, just reorganizing stuff. :)
symtab: Cleanup and reorganization. Finally fixes #7.

The main, important modules are in much better shape than when I first
started. Also, I'm much more aware of the parts that need to be redone/are
terrible.

I'm skipping over debug, even though I'm well aware that it's not all that
great. The reason is that I intend to change show into a function, as well as
break the code dumper into individual functions (the whole switchtable thing
is getting really, really nasty).

Time to add new things again! :)