rework analyzer to get it ready for parallel merge
use parallel map for includes, subninjas
update profile()
allow names to start with an underscore
add names to graphs, clean up reprs
checkpoint reworking of subninja/include handling
copy rules over from subninja
handle ctrl-c
tune sleep() calls in build
tweak profile script
fix bug in find_nodes_to_build(), use sets to test for membership
fix update elision
bump version to 0.5: significant profiling; dryrun works on chrome