GitLab

- add "geo" versions of add/RemovePhysicalGroup in anticipation of move of "master" physical group definition in GModel (we will need to keep the built-in kernel defintion as well, since built-in CAD operations track physicals)
- more explicit mentions of CAD kernel in api docs

check dimensions of numpy arrays for "simple" input vectors as well, to detect wrong user input (e.g. passing a list of pairs as a list of ints)