[v1.0.15] Add "Stop" functionality and key

Add a "Stop" feature to stop the selected character's movement. Often, the player makes the party move by clicking on a distant spot, and unknown discoveries (trap, enemies, treasure, other route) would conveniently see the party stop. The only way to do that now is pause and click somewhere else, which is not user-friendly.

PS: you should add more tags to sort out reports more easily