Add command prompt

This adds support for vim-style command mode. The command mode can be
entered with pressing ":" (by default, the key binding is configurable).

Currently, no command is supported. Support for various commands will be
added later.

Signed-off-by: Lukas Fleischer <calcurse@cryptocrack.de>

src/calcurse.h

@@ -434,6 +434,7 @@ enum key {
 	KEY_GENERIC_SCROLL_DOWN,
 	KEY_GENERIC_SCROLL_UP,
 	KEY_GENERIC_GOTO_TODAY,
+	KEY_GENERIC_CMD,
 
 	KEY_MOVE_RIGHT,
 	KEY_MOVE_LEFT,