statusline-format: add %p placeholder for current path

Allow showing the current working directory in the statusline via
[statusline] render-format=%p, which is useful if the user changes
directories often.

Signed-off-by: Bence Ferdinandy <bence@ferdinandy.com>
Tested-by: Tim Culverhouse <tim@timculverhouse.com>
Acked-by: Robin Jarry <robin@jarry.cc>

commands/cd.go

@@ -60,6 +60,7 @@ func (ChangeDirectory) Execute(aerc *widgets.Aerc, args []string) error {
 	}
 	if err := os.Chdir(target); err == nil {
 		previousDir = cwd
+		aerc.UpdateStatus()
 	}
 	return err
 }