Add transitively skipped assertions option

[CatsAreFluffy]

For example, if I was trying to prove a theorem without using ~ ax-rep, I would want to skip not just ax-rep, but all theorems using ax-rep.

[expln]

Ok, that makes sense. I will implement it.

[expln]

This is implemented on dev.

Please read this comment to understand the new settings which allow to skip some assertion and all the theorems depending on it.

In order to skip ax-rep and all theorems using ax-rep, you may set the new settings as follows: