Add strict key checking mode

[izulin]

Is your feature request related to a problem? Please describe.
It is easy to make a promise that is indeed later broken. This might led to a runtime error later down the line.

Describe the solution you'd like
Add a mode that would check at runtime:

• every universe equality/subset/disjointness promise
• that keys produced by with_id_from are in fact disjoint
• each -1 in a row is matched with preceding +1
• ... (probably more usages)