Rewrite the dependency engine to be based on 'effects'

[aronisstav]

Splitting down each builtin to reads and writes to specific locations should make dependency description easier.

This can be extended to simplify 'happens before' assignment too, if vector clocks are also tied to effects (as per original Flanagan & Godefroid suggestion).

[aronisstav]

Consider refining this in such a way that e.g. 'failing operations' don't have all the effects of an identical successful operation. e.g. a register first just 'reads' whether a name and pid are not registered (and may fail) and then 'writes' the new association. If it has failed it cannot interact with a 'whereis' for the same name, as it never wrote the name.

[aronisstav]

Migrated to aronisstav#28.