Merge pull request #9 from timo/master

Make Build.pm work with current panda.
Fix debugger on latest Rakudo.
Remove workaround that's no longer needed.
Ensure updated $/ in grammar debugging.
Make $<foo> and $0 dump nicer.
Un-bit-rot tracepoint show.
Add breakpoint setting in code with "#?BREAK".
Remove mention of perl6_group, which went away.
Unbust debugger against latest Rakudo.
Chase changes to END handling.
Eliminate a pir::.
Better handling of END on quit; fixes #13.

Now, when you quit and there are END blocks queued up, you are asked
if you wish to run them. Doing so will return the prompt to a saner
state if you happened to be in an exceptional state.
ignore generated files
Some pir:: -> nqp:: in prep for JVM support.
Stop using deprecated .exists method.
Some JVM compatibility fixes.
Final code tweaks to support Parrot and JVM.

Still need to get proper build/runner stuff in place for JVM, but that
should be all that's needed now.