advtrains_supplemental/advtrains_freight_train: Freight train for advtrains (made by MBB, implemented by Smacker and gpcf, currently maintained by the Advtrains Supplemental organisation)

mbb c37a044de4 Initial commit		7 lat temu
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advtrains_engine_diesel.b3d	c37a044de4 Initial commit	7 lat temu
advtrains_wagon_gravel.b3d	c37a044de4 Initial commit	7 lat temu
advtrains_wagon_lava.b3d	c37a044de4 Initial commit	7 lat temu
advtrains_wagon_stick.b3d	c37a044de4 Initial commit	7 lat temu
advtrains_wagon_tree.b3d	c37a044de4 Initial commit	7 lat temu