Rework personalities and some plug-in handling

<!-- markdown --> Users: * Precommit's bundled personalities have been removed as they are all out of date. * Personalities will be loaded from `.yetus/personality.sh` by default. * User-plugins will be loaded from`.yetus/plugins.d` by default. * The `test-patch.d` directory has been renamed to `plugins.` * `--project` can no longer be used to load a personality from a plugin directory. Developers: * BASEDIR is now absolute'd sooner. * PERSONALITY and USER_PLUGIN_DIR will almost always have a value now. * PERSONALITY is now guaranteed to load after plugins. * `personality_modules` and `personality_file_tests` are no longer defined by default. Instead, plugins, core code, etc, (basically, anything not a personality) should call `personality_modules_wrapper` and `personality_file_tests_wrapper`. These functions will be redirect to the correct function. * PROJECT_NAME_* is now honored for loading many of the personality-specific functions.