Bare-bones dex code generator.

This is functional but incomplete. In particular, the following
are still coming:
 - instructions for cast/instanceof/arrays/float comparison/try/catch
 - debug information
 - annotations

The API is also incomplete. When this is done I'm going to remove
the type parameters to see if that's a net win. I suspect it will
be because generics currently hurt the ability to do assignments
between unknown types - you can't currently assign from Label<?> to
Label<?>, for example.

I'm anticipating changes to the way Code instances are created.
In the current API these are created without an attached method and
later attached to a method with Method.declare(). This doesn't work
very well, particularly since the code blocks don't know how many
parameters they take, whether they're static, or what their return
type is. I'm tempted to make declare() return a writable Code instance,
or to simply combine the Code and Method classes.

This code can benefit from more error detection. It's currently quite
easy to do bad things with labels: use them on the wrong Code instance,
reuse them, don't use them, etc. Better error checking is due here.

Change-Id: I4fe20552f2c571e41bedba6ff9db6686688d97ee
http://code.google.com/p/android/issues/detail?id=6322
22 files changed