For testing non-core files, just `load ../test_helper_libs` after `load ../test_helper` instead of trying to guess which libs must be loaded, in which order, for testing to succeed.
`_command_exists` spews log messages, so our test log is littered with `_log_debug not found`. This fixes that too.
Wrap init code in a function and call the function immediately. Several plugins do this, and it allows us to more easily implement a hooks-based system in the future.
Alsö, avoid external binary `which`. Use built-in `type -P` instead. Uppercase `-P` forces a path search to avoid hashed matches and functions/aliases and whatnot.
John D Pell
buhl
Noah Gorny
Nils Winkler