Add in-program command line

From @kliment on Fri Feb 09 2018 06:41:34 GMT+0000 (UTC)

Similar to autocad and eagle - allows both rapid tool switching to lesser-used tools that don’t have their own keyboard shortcut and also entering things like coordinates precisely.

Copied from original issue: https://github.com/LibrePCB/librepcb-rfcs/issues/2

From @dbrgn on Thu Feb 15 2018 09:46:44 GMT+0000 (UTC)

We could also take some inspiration from the command palette in VS Code:

Plugins can also register custom commands in there. For example, here for the Rust plugin: