Trying to have a better git report.
Mail git repport is prettier.
no need to see git output
check_if_work_tree_clean was renamed in work_tree_clean, mail requires an email address
Test added for git where posing trouble
We must use to launch function in a subshell, other wise the whole script exit with the instruction 'exit 1' or 'exit 0'. We must use " around variable for test. Otherwise, we get a Unexpected operator error.
Takes into account remarks from #343 (until comment 7)
Script support git as described #343 to implement #191
