[LDCad] Shadow file contributions

[Roland Melkert]

First of all is it ok that I just add PRs to the github repo?

Yes, I'll try to merge it without too long a delay (probably in the weekends).

And second. For this example. Does it matter what orientation the lines are in for the window/door?

It depends on the meta type some account for symmetry while others will snap 'dumb' meaning the dragged part will rotate so the meta xyz matches the destination mata's xyz.

The generic snap meta also has an option for it.