Make technic_worldgen loadable before technic

There was a small amount of dependency of technic_worldgen on the
technic mod, for configuration loading and the top-level "technic" table.
Resolve that by sharing the configuration and top-level table between the
two mods.  This means that technic_worldgen can be loaded before technic,
permitting other mods to depend on it without depending on technic.

technic/init.lua

@@ -2,7 +2,7 @@
 -- namespace: technic
 -- (c) 2012-2013 by RealBadAngel <mk@realbadangel.pl>
 
-technic = {}
+technic = technic or {}
 
 local load_start = os.clock()
 local modpath = minetest.get_modpath("technic")