Decode the raw data for the *-payload instructions

Before, these instructions stored raw data as `[Word16]`.  This change
decodes them properly*.  The switch payloads are decoded into `Int32`
offsets.  The array-data-payload is decoded such that all different
types of constant are promoted to Int64 (this includes float types,
since we can't know what the real type of a constant is until it is
used).  The decoding of actual Java longs might not be right - that
still requires a test or three.
Translate the fill-array instruction

This needed a few supporting changes (mostly because we need to be able
to find the array-data-payload, which is at a relative offset from the
actual fill-array instruction).
Change the representation of interfaces (and translate them)

The old representation had `Interface` as its own type in the SSA IR.
This doesn't work very well because many of the interfaces that are
implemented in any given Dex file are not actually represented in the
Dex file.  Instead, we just store the list of `Type`s.
Translate Invoke instructions
Remove an unused type system extension
Big cleanup pass

Moved a few modules supporting the SSA transformation into
Dalvik.SSA.Internal.  Also moved a few functions from Dalvik.SSA into
this submodule hierarchy.
Remove an obsolete comment
Get rid of a now-unnecessary helper function
Mark phi nodes as having Unknown type.

Poking at the incoming values could be pretty dangerous.  A careful
approach looking only at values that are already defined could work, but
isn't actually guaranteed to find an answer anyway.
Translate constants

For now, we basically punt all numeric constants to Int since we don't
know much more about them.
Have the SSA labeling code use Int instead of Int64

This just makes using that code a bit simpler.  If you overflow an Int
on a 32 bit system, you can't store that many SSA values anyway since
you don't have enough memory.
Add method parameters to the initial Label -> Value map

Now references to parameters in method bodies can be resolved to SSA
values.  This was the last piece required before testing can begin.