Added Terraflint, acquired from Firestone material.

Also added SplitTerraflint dummy definition to produce in the Alchemy Lab. Will provide you with 3 small flints.
Added the SplitTerraflint definition in scenario where it seemed fitting.
Halved lifting time of carry heavy objects.
Applied Maikel's balancing.

See http://forum.openclonk.org/topic_show.pl?tid=2972