Suggest default # of CPUs (e.g. use default from computer?) and of pools (some simple heuristics?)

**Is your feature request related to a problem? Please describe.**
By default the app sets 1 CPU and 1 pool (I think, at least for me). I need to be expert to know how many I should use.

**Describe the solution you'd like**
I guess I always want to use the max # of CPUs on the computer (on 1 node) and scale at least to full 1 node by default, and use some pools when memory is not an issue and I have enough k-points.
(BTW, apparently now QE has a auto-parallelisation feature? @mbercx did you try it? We should probably check and use it, at least for the QE app! If you don't have time maybe someone else could try it out @unkcpz or @superstar54 ?)