Add ‘skip to next turn’ choice to CLI.

[gseitz]

This is a first shot at adding "skip to next turn". I'm not sure if it's desirable to differentiate between various main phases, eg. offer "skip to main phase" in the up beginning phase. I imagine that especially in the CLI, the added option would clutter up the screen.

This PR is just intended as a basis for discussion, not necessarily for immediate pulling :)