Regarding the latest devlog and skill-based mining: in a less rigid system, making this Raw-based would be a net plus. I.e. a mineral definition would have some entries for specific things the destruction of the tile would yield, with modifiers based on different things, skills included. You could use this system to, for instance, completely omit the CLUSTER_SINGLE placement of gems, instead using a ridiculously low chance of said gem dropping randomly from different relevant minerals, and allow ore and gem veins to produce common stone alongside their usual material, all based on relevant skills of the miner (i.e. if the miner is also a gem expert, he'll have more chance to get better gems, etc).
On dumping things from carts, you could have two kinds of "dump tracks". One would be a mechanically activated "tumbler", a device that turns a stationary cart over without having it leave the track, effectively dumping its contents onto an adjacent tile as defined during placement. Another would be a sort of a "tilted track", a segment of track with railings that keep the cart on while it is turned sideways, dumping its contents alongside the track without the need to stop. This would likely be a fixed length (3- or 5-long) segment with 4 selectable facings. No idea how to represent the tilted track in ASCII, though.