* Start of pattern matcher

recursive graph matcher, pattern node

add matcher.cpp

add files for matcher, graph_rewrite

add const to on_match_class

fix comp errors

reshuffle pattern matching code across corresponding files

fix comment

run clang-format

graph_rewrite replace_node

getting simple test cases to work

op/pattern.cpp

toward graph_rewrite tests

older matcher API

before clean up tests

before rebase

build bbrks

more tests

clean up

more clean-up

more cleanup 2

more clean up 3

clean up 4

clang errors

clang errors2

apply code format

move match_class to matcher

major clean up after moving match_class to matcher.cpp

removing tracing changes

rebased as of 11/8

make matcher use i/o descs to traverse the graph; change replace_io

switching to io tds

graph_rewrite tests fail

all tests pass

formatting

unhandle outputs explicitly for now

reset permissions back to 0644; bad bad windows

fixes after rebase

* fixes

* addressing Scott's feedback