Replace ABM functions with per-node timers

[h-v-smacker]

Since mesecons are machines, and therefore much more rare than "natural" nodes, it makes sense to activate them using callback for node timer, as opposed to introducing wide-sweep ABM scans. In total, there are 4 files with 9 registered ABMs: one for torch, two for the turbine and solar panel, and 4 for detectors. I replaced them with per-node timer events and an LBM to migrate existing nodes (activate their timers).

[numberZero]

minetest/minetest#4050