Start processing use more smartly.

This handles it through the usual longname parser, meaning we now can
pick out the name itself from any colonpairs.
Pass use/need colonpairs to module loader.

This also catches any use of :from<...> and complains for now; this is
the hook where :from<jvm> support will go.
Add a mechanism to register :from loaders.
Refactor to make alternative loaders easier.

This relaxes what is returned to just be something hash-ish, not a
full-blown context.
Very basic :from<java> support.

The objects are decidedly lacking in sugar so far, not to mention the
marshalling of Perl 6 types will need a lot of work. But you can do:

    use java::lang::System:from<java>;
    say System.currentTimeMillis();

And it works.
Give :from<java> support for a :jar<...> also.
Prepare for Rakudo-specific tweaks to JVM interop.
Give objects from Java a JavaHOW REPR.

This will enable us to get them to behave a bit 6ier.
Objects from Java pretend to be Any and Mu.
Merge branch 'use-from-java' into nom
Fix require regression.