Remove stat-specific code from pilot_canEquip

Since it was decided to allow players to create non-spaceworthy ships
in the equipment screen, this function no longer cares about stats,
only slot sizes and a handful of edge cases.
Add escorts when loading a game

This prevents the fighter bay from being reloaded with new fighters
when the current ones are still deployed in space.
Always restore the focused line in the keybinds list, if possible
Merge branch 'master' of github.com:Deiz/naev into rebalance
Rename numerous core systems in preparation for rebalancing
Initial rebalance of core systems

This commit only touches the XML; equip scripts and missions have yet
to be updated.
Renamed 15 core systems throughout Lua and XML
Completed renaming of core systems in XML and Lua

As with the engine rebalance, the now-unused outfits have not been
deleted, they've just been removed from all techs except "All Outfits"