Add JNA 3rd party library.
Stub native call ops.
Stub the NativeCall and CPointer REPRs.
Set correct argument signatures for native call ops.
Add JNA to build and runtime JARs.
First implementation of nqp::buildnativecall.
Move constants to enum from static final byte FOO.
Build NativeCallInstance.{arg_types,ret_type} in nqp::buildnativecall.
Basic call handling and converting between NQP and JNA types.

This means that we support int, num, str and cpointer as arguments and return
values, which in turn means that we pass the basic sanity tests in the NQP
test suite.
Run native call tests as part of the standard test target.
Stub the CArray and CStr REPRs.

We need these to get NativeCall.pm6 to compile.
Stub nqp::nativecallrefresh.

Also needed to get NativeCall.pm6 to compile.
Add nqp::getcfh op on Parrot backend.

Maps to what is used to provide getc in Rakudo now; will allow us to
provide a JVM implementation also.
document new opcode

jnthn++
fix style nit
fix formatting for trig ops.
First pass at nqp::getcfh on JVM.
Fix bug with integer ** quantifiers

/ a ** 2_0 / previously matched "a" two times.
Now uses the .ast of <decint>.
Fix empty range error in ** quantifier
Prepare QAST -> JVM compiler for closure changes.

We'll experiment with this on MoarVM first; this just does enough to
have QAST -> JVM not choke on some small changes to NQP.