flood_water would occasionally corrupt pmap by moving the pmap entry at i's location even if the entry itself didn't refer to i. pmap updates are tricky, they are best handled by Simulation::move.
Saving blockair/blockairh is nice because RecalculateBlockAirMaps uses the sim rng, which means the sim rng would get advanced in Simulation::Load. Also rename RecalculateBlockAirMaps to ApproximateBlockAirMaps because that's what it is, an approximation, and it's needed only if there are no block air maps in the save.
Simulation::frameCount keeps track of frames elapsed since the beginning of the simulation, zeroed at clear_sim. It overflows when it reaches the 64-bit limit, which means anything that depends on it should either handle this, or not fail catastrophically. sandcolour (the only thing that depends on it as of now) is a good example of the latter: sandcolour has a periodicity of 360 frames, which means that there is one sandcolour period that is cut short by the overflow. This is not "handled" (the period is cut short, which is detectable by users) but is not catastrophic either (it's not a big deal, and it won't ever happen unless someone hacks the save).
Also restrict saves with determinism data to 98.0.
Achieved by adding a new element property called CarriesTypeIn, whose bits signal to save loading code which properties of particles of the element class in question carry element IDs. The bits in this property are numbered the same way as sim.FIELD_* constants for consistency. One would signal from Lua that a custom element carries element IDs in its tmp like this:
elem.property(id, "CarriesTypeIn", 2 ^ sim.FIELD_TMP)
"Carrying an element ID in a property" is to be interpreted as follows: the property is treated as a combination of a PMAPBITS-bit (so, currently 9-bit) unsigned integer lower part holding an element ID and a 32-PMAPBITS-bit (so, currently 23-bit) signed integer upper part holding whatever makes sense for the element. CONV, for example, uses this signed integer in its ctype as the extra "v" parameter for particle creation.
Some checks on particles, most importantly whether their element IDs refers to an enabled element, were done _before_ in-save element IDs are mapped to in-simulation element IDs. This resulted in some particles being removed if their IDs were unlucky enough.
Namely: no, yes, and yes and ask at startup.
The install_check option is thus replaced by the can_install option. -Dinstall_check=true maps to -Dcan_install=yes_check, while -Dinstall_check=false maps to -Dcan_install=yes. -Dcan_install=no is new and is recommended for downstream packaging, where -Dinstall_check=false was historically used.
Also improve error messages about bad configuration here and there and scatter configuration code in subdirectories, where they can be closer to their areas of effect.
More precisely, refactor the code responsible for routing these GameController events to the Lua side. The issue with the previous solution was it relied on preprocessor macros to switch between Lua-ful and Lua-less builds.
This restrict effects of paste-time de-stacking to positions under particles being pasted. If this is not done, particles beyond the paste area can be wrongfully killed, see #889.
Some operator[]s that know the size of the container they wrap like to assert(index >= 0 && index < size), which is bad for us because we sometimes use &container[size]. This is not undefined behaviour until that pointer is dereferenced, but certain operator[]s choose to ignore this fact and err on the side of caution. The solution is to use &container[0] + size instead of &container[size].
I took extra care to not mess up signedness in readOPS in ab600780d0, but apparently didn't do the same in readPSv.
Also fix a bound check that was broken since aac6b7258c. It's a good thing this was broken, because this allowed negative type values from broken signedness readPSv to get past and cause a crash later on, rather than just cause particles to disappear or something.
