Slaves (child processes running tests for regrtest -jN) now inherit
--memlimit/-M, --threshold/-t and --nowindows/-n options.
* -M, -t and -n are now supported with -jN
* Factorize code to run tests.
* run_test_in_subprocess() now pass the whole "ns" namespace to the child
process.
Start to split regrtest.py into smaller parts with the creation of
Lib/test/libregrtest/cmdline.py: code to handle the command line, especially
parsing command line arguments. This part of the code is tested by
test_regrtest.
Brett Cannon
Victor Stinner