start using gtest for c++ unit testing
move test output to tmp directory
add local tree drawing functions
add comments, remove debug printfs
fix add_spr_branch last_state displayed bug
improve test_trans_switch to be deterministic
add test_trans_switch data
add test data for test_trans
Merge branch 'master' into start-cpp-tests
add local tree parsing tests
update makefile
add test for spr probabilities