Add better control over expression timeouts.
* //timeout command can be used to change player's current timeout.
* Config now also has a max timeout, can be bypassed with permission
* Timeout of < 0 will let expressions run indefinitely.
* Said expressions won't run on a separate thread, slightly reducing the
overhead from context switching. For large //gen commands, for example,
this can actually increase speed.
Instead of trying to maintain a list of "natural terrain blocks", just
let the user specify a mask of blocks to use for the height map filter.
https://gfycat.com/severaljauntycondor
The initial material is held in the factory, but if a brush was previously bound, that pattern is used.
Now, using `//br set` will clear the previous material, allowing the OperationFactory's material to work.
This can be changed later with `/mat`, which will once again set the fill on the tool, overriding the factory's context.
* `//set ##*tag` sets all states in the tag (not just default state per type)
* `//set ^type` is a pattern changing block type but copying all valid existing states
* `//set ^[prop=val,...]` sets the property `prop` to `val` wherever the existing block has that property
* `//set ^type[prop=val,...]` does both of the above
Those work anywhere a pattern is taken, of course.
* The mask syntax `^[prop=val]` matches blocks with the property `prop` set to `val`, or blocks that don't have the property at all.
* The mask syntax `^=[prop=val]` only matches blocks that have the property.
Those work anywhere a mask is taken, of course. (`//mask`, `//gmask`, `//replace`, etc)
The `//drain` command now takes `-w` flag that removes the waterlogged state from blocks (in addition to removing water, as before).
Unfortunately this is a bit slower than before since we can't cache block
id & data values. However, applying patterns generally isn't too expensive,
and hollow regions were entirely broken before.
