1. Create behat datadir within behat_dataroot not at same level
2. Define suffix for link and not use hard-coded values
3. Renamed ns_parallel to run.php
4. Rename variables to best understand them
5. Added support for each run to specify db, prefix, rerun and profile.
6. Showing number of steps in each line of parallel run.
Improvements include:
* Alternative location might be useful when server administrator wants to maintain
a local copy of component cache instead of using shared $CFG->cachedir.
* Component caching is now enabled in behat tests which should improve performance.
* Standardised ignoring of component caching.
* Fixed debug mode in ABORT_AFTER_CONFIG scripts.
* General documentation improvements.