Maploader rewriting

_Since this has been PR to and merged by /tg and /vg., there's no reason not to propose this rewrite to Bay..._

# Original PR :

Rewrote maploader to act faster and better handle set variables (a.k.a basically reimplemented BYOND map parser to load DM maps at init or in-game).

__Most notably :__
* better loading times, less processing loops, got ride of the _old_turf_ checking, since we're building the map on area/turf/space

Had to make one assumption, that is there's always an /area AND /turf on a given tiles (if any other project where that assertion fails, wants to use it i've provided a commented code sample that takes that into account)
* full path procs and commented code

* __lists variables are now taken into account (simples and associatives)__

To think it began with simply adding that...
That means it's now possible to use multiple access, cameras (using my other PR), etc on away missions

* every character can now be used inside a string without fear of breaking the loading process (before 
using ; could mess the whole thing up)

I've respected the BYOND logic of instanciating : area => turf => obj/mob.

This has been thoroughly tested and everything found working so far.
Obviously, large parts of BYOND being undocumented (notably the creation process of /area and /turf), there _may_ be some discrepancies left...