- Replaced 'EXP' with "Playtime' in most admin-visible locations. The
system is still invisible to normal players.
- Changed the types of exp you can accumulate from 'all', 'eng', 'sup',
etc to more human-friendly names like 'Crew', 'Engineering', and
'Supply'.
- Eliminated some copy-paste.
- Added a new configuration option: use_exp_restrictions_heads_hours.
When enabled and set to a >0 value, it overrides all head/ai job
playtime requirements, instead substituting that number of hours.