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_worldgen/config.lua

@@ -0,0 +1,15 @@
+technic.config = technic.config or Settings(minetest.get_worldpath().."/technic.conf")
+
+local conf_table = technic.config:to_table()
+
+local defaults = {
+	enable_granite_generation = "true",
+	enable_marble_generation = "true",
+	enable_rubber_tree_generation = "true",
+}
+
+for k, v in pairs(defaults) do
+	if conf_table[k] == nil then
+		technic.config:set(k, v)
+	end
+end

technic_worldgen/depends.txt

@@ -1,4 +1,3 @@
 default
-technic
 intllib?
 mg?

technic_worldgen/init.lua

@@ -1,5 +1,6 @@
 local modpath = minetest.get_modpath("technic_worldgen")
 
+technic = technic or {}
 technic.worldgen = {}
 if intllib then
 	technic.worldgen.gettext = intllib.Getter()
@@ -7,6 +8,7 @@ else
 	technic.worldgen.gettext = function(s) return s end
 end
 
+dofile(modpath.."/config.lua")
 dofile(modpath.."/nodes.lua")
 dofile(modpath.."/oregen.lua")
 dofile(modpath.."/crafts.lua")