feat(ipc): add 'get cursorpos' and 'get option <name>' queries

mmsg/mmsg.1

@@ -21,6 +21,17 @@ All \fBget\fR commands print a single JSON object and then close the connection.
 \fBget version\fR
 Return compositor version.
 .TP
+\fBget cursorpos\fR
+Return the global pointer position (\fBx\fR, \fBy\fR) and the monitor under it
+(\fBnull\fR if over no output).
+.TP
+\fBget option \fIname\fR
+Return the current value of a scalar config option. Numbers are returned as
+numbers, colors as \fB0xRRGGBBAA\fR strings, bezier curves as 4-element arrays.
+Values round-trip through \fBdispatch setoption,\fIname\fB,\fIvalue\fR, except
+the comma-list options \fBcircle_layout\fR and \fBscroller_proportion_preset\fR
+(readable as arrays, but written via the config file).
+.TP
 \fBget keymode\fR
 Return current keymode.
 .TP

mmsg/mmsg.c

@@ -12,6 +12,10 @@ static void usage(void) {
 	printf("One-shot queries (get):\n");
 	printf(
 		"  get version                              Show compositor version\n");
+	printf("  get cursorpos                            Show pointer position + "
+		   "monitor\n");
+	printf("  get option <name>                        Show current value of a "
+		   "config option\n");
 	printf("  get keymode                              Show current keymode\n");
 	printf("  get keyboardlayout                       Show current keyboard "
 		   "layout\n");