Add setmultispec mechanism.

When we have onlystar protos with simple signatures, there's no reason
to call the proto, to have it wrap the args in an object to then use
to do a lookup in a multi cache. Provide a mechanism to try the cache
right away, falling back to the proto (which may populate the cache).
Small fixes to MVM_string_(latin1|windows1252)_encode_substr
Merge branch 'spesh'

Conflicts:
	lib/MAST/Ops.nqp
	src/core/interp.c
	src/core/oplabels.h
	src/core/oplist
	src/core/ops.c
	src/core/ops.h
Add a way to flag a frame as a "thunk".

This will allow us to ignore it in certain situations when considering
caller and outer chains.
Add ctx[outer|caller]skipthunks ops.
Make backtrace generation ignore thunks.
When readline/linenoise see EOF, mark handle eof

This lets you use ^D to exit the rakudo/nqp REPL.
Merge pull request #90 from retupmoca/master

When readline/linenoise see EOF, mark handle eof
Set hint for invokespec and multispec.

Means the attribute lookups go a good amount faster.
Improve the VM exit strategy.

It now doesn't try to do all the cleanup work by default, instead
leaving it to the OS, which can no doubt do it faster. There is now
a --full-cleanup flag for requesting full cleanup, however. In either
case, special effort to gracefully join foreground threads is made,
so "Thread.start({ sleep 1; say 'bye' }); say 'hi'" in Perl 6 will now
output hi\nbye\n reliably (and passing :app_lifetime will not show the
bye\n, and seems to exit cleanly too provided --full-cleanup isn't
passed).
Unbreak CGOTO compilation.

It can't cope with ops in oplist but having no stub in interp.c.
Correctly handle temp roots stack in callbacks.
add sched_yield for NetBSD
Merge pull request #91 from stmuk/master

add sched_yield for NetBSD
Fix callsite size calculation in tweak_cs.

Avoids trying to access memory beyond its allocated boundary. Found by
nwc10++ using ASAN/Valgrind.
Fix buffer overflow in UTF-16 encoding.
Make sure is_interned is zeroed as needed.

Patch partially thanks to nwc10++ (the args.c case), who also found
the general issue. Other 3 changes are other places vulnerable to the
same kind of bug.
Merge branch 'master' into named_to_positional

Conflicts:
	src/core/args.c
	src/core/frame.c