Added :: operator on all objects.

The verison in gracelib.c is known to compile; the version
in gracelib.js may not, because I'm doing this on an
æroplane, and can't test it.
Added :: to gracelib.js

This time it works for Strings and Numbers.
Added a version of collections.grace

This should becoem part of the build.
mgcollectiosn should be replaced by a compatability stub.
However, because of the compile-it-three-times strategy,
I'm guessing that this will ahve to propogate through a
few commits before it can be imported by the kg compilers.
Added collections library.

Also added a stub version of mgcollections, which is designed
to replace mgcollections at some time in the future.