util: add an optional timestamp parameter to makedate This will be used by the upcoming shelve extension.

util: rename ct variable in makedate to timestamp

merge: add a files method to the mergestate class This will be used in the upcoming shelve extension.

histedit: raise ImportError when demandloading is enabled

run-tests: add --loop support This makes it easy to run tests repeatedly at high loads to look for test failures.

run-tests: --interactive and --jobs no longer conflict

run-tests: sort certain slow tests earlier by keyword There are a few tests that evade the size heuristic

run-tests: drop unused resultslock

run-tests: drop options.child and users

run-tests: remove runchildren, now unused

run-tests: schedule largest tests first

run-tests: introduce thread scheduler

run-tests: use count to calculate port to use This will keep threads from using the same server ports

run-tests: introduce threadtmp directory

run-tests: add abort flag This will be used to help threads clean up gracefully