add tab stops to snippets, plus a few bug fixes

snippets/hdrum1

@@ -6,9 +6,9 @@
 # --
 -- @hdrum1
 d'drum $ stack [
-  n "[1*2, 0*8, [~!! [~!! 0] ! ~!!]]/8" # s "drum",
+  n "[1*2, 0*8, [~!! [~!! 0] ! ~!!]]/8" # s "${1:drum}",
   -- whenmod 3 2 (density 2) $ -- (3)
   -- withmod 11 5 0.5 1 (density 2) $ -- (2)
-  n "~ 0" # s "kit"
-  -- n "[[~ 0] [[2!! ~]/4 0]]/2" # s "kit" -- (1)
+  n "~ 0" # s "${2:kit}"
+  -- n "[[~ 0] [[2!! ~]/4 0]]/2" # s "$2" -- (1)
   ]