Exhaust velocity increase
don't flip the ship for main-thruster deceleration during coast phase

As requested on the forum:
http://pioneerspacesim.net/forum/viewtopic.php?f=3&t=198

(and possibly in other places)
LuaSerializer: Change the pickle interface to specify a default key in the header
LuaSerializer: Split the ref table initialization into its own methods.
LuaRef: Add serialization support
PropertyMap: Add serialization support
TradeShips.lua takes far too long to process things, it requests vast volumes of space to analyse.
Reduce the maximum and ensure the minimum distances requested of GetNearbySystems so no more requesting 67.7 light years worth of systems!
Also start with the half-distance and use it if it is acceptable, only go further if it's not.
Improve the chances that we've already generated the relevant SystemPath by ordering them nearest to furthest when we fill the cache.
As the other improvements have highlighted it seems we might need some more profile logging in the GasGiant code.
Disable the save button when in hyperspace
Merge branch 'disable_hyperspace_save'
Changelog
Merge remote-tracking branch 'jpab/defer-retro-turn'
auto-commit: translation updates
better documentation of lawlessness
Merge branch 'luaref_serialize'
auto-commit: translation updates
LuaTable: add return values to help chain method calls
New pi_lua_multiple_push to push as many stuff as one wants
Add a pi_lua_generic_push function for LuaRef