implements stat
Merge pull request #9 from thecabinet/stat

implements stat
Add a REPR for context references.

We don't make contexts have to be GCable, 6model objects. But if we
want to talk about them first class, they need objectifying. This will
provide that wrapping.
Implement nqp::ctx, nqp::ctxouter, nqp::ctxcaller.
Implement nqp::curcode() and nqp::callercode().
Update ROADMAP.
Implement compiler registry (getcomp/bindcomp).
Implement getcurhllsym and bindcurhllsym.
Implement QAST::VarWithFallback.
Test QAST::VarWithFallback.
ROADMAP update.
Start to prepare cross-compiler for libraries.

Previously, we always created a Java class file with the same name.
This generates unique names, but provides a way to get control over it
when compiling so you can get something that can be started directly
by invoking the JVM with that class name also.
Implement nqp::loadbytecode.

Loads the class file for compilation unit, triggers deserialization
and runs any load-time code.
Update .gitignore.
Fix temp allocation thinko.
Add nqp::ctxlexpad.

General lexpad introspection still needs more work though.
Don't lose caller in library loading.
Implement object lexical lookup through context.

Need to do a bunch of other cases, but this is what ModuleLoader needs.
Use stable-sc option always.
Start cross-compiling an nqp-mo and ModuleLoader.

The nqp-mo is very close to the real NQP one, just with some Parrot
specific bits and mixins (NYI) commented out. ModuleLoader has a few
more bits commented out, but is very close.