Fix replacing note with custom instrument not triggering compatibility check

Fixes #88

Author: Bentroen

scripts/change_block_manual/change_block_manual.gml

@@ -22,6 +22,9 @@ if (ins.loaded) play_sound(ins, key, vel, pan, pit)
 
 history_set(h_changeblock, xx, yy, ins, key, vel, pan, pit, pins, pkey, pvel, ppan, ppit)
 changed = 1
+
+if (!pins.user && ins.user) block_custom += 1
+if (pins.user && !ins.user) block_custom -= 1
 if (pkey >= 33 && pkey <= 57 && (key < 33 || key > 57)) block_outside += 1
 if (key >= 33 && key <= 57 && (pkey < 33 || pkey > 57)) block_outside -= 1
 if (ppit = 0 && pit != 0) block_pitched += 1