Create potion-mode.el

A simple generic-mode based mode for edition Potion code, with
syntax highlighting and handling of ":" and "." as matching brackets.
Added LANG directive per Gerd Pokorra
Don't think _why's answering email.
Merge pull request #22 from seano-cpan/master

Add potion-mode.el for Emacs -- Thanks!
backport p2 enhancements: -e, potion_cmd_exec, -D?

add filename to potion_parse, add potion_cmd_exec, add DEBUG_PARSE_VERBOSE,
use dump*?_str,p macros
prepare other compilers (c, exec)
remove verbose (replaced by P->flags |= DEBUG_VERBOSE)
bump POTION_MINOR=1

broke 2 JIT tests: test/closures/long.pn SEGV, test/closures/upvals.pn <>
rename .g to .y (yacc-style)
add test/runtests.sh (potion version only)

usage: test/runtests.sh [test-file]
or     cmd="valgrind ./potion" test/runtests.sh [test-file]
Merge branch 'g-y'
Merge remote-tracking branch 'upstream/master'

Fixed conflicts:
	Makefile
(removed silent contact address)
add test/runtests.sh (potion + p2)
rename .g to .y (yacc-style)
Merge remote-tracking branch 'origin/master' into p2

Fixed Conflicts:
	Makefile
	core/load.c
	core/potion.h
	core/syntax.g
	core/syntax.y
	front/potion.c
	syn/syntax.y
	test/runtests.sh