change branch length output file suffix from BL to bl
add tests of ms vs hybridLambda
add moments to tmrca tests
update ms vs hybridLambda test case files
rework on Si_table fieled
add sample stats tests for generated sequences.
add test for pairwise, throwing an error
correct tree string out put with ;, at the end
rework on convert hybrid-lambda out put to ms format in order to use sample_stats
problem with long internal branches,
problem with long internal branches structures
Update README.md
first attmpt to use git submodule
first attmpt to use git submodule
merged dev to master