additional syntactic sugar

- allow multiple names in infix, typesig, and dcon defs
- align fixities with Idris

tests/black/Oper.newt

@@ -11,10 +11,8 @@ module Oper
 -- long term, I might want TopContext in the parser, and parse a top-level
 -- declaration at a time (for incremental updates), but much longer term.
 
-infixl 4 _+_
-infixl 4 _-_
-infixl 5 _*_
-infixl 5 _/_
+infixl 8 _+_ _-_
+infixl 9 _*_ _/_
 
 ptype Int
 ptype String
@@ -33,7 +31,7 @@ _+_ x y = plus x y
 test : Int -> Int
 test x = 42 + x * 3 + 2
 
-infixr 2 _,_
+infixr 0 _,_
 data Pair : U -> U -> U where
   _,_ : {A B : U} -> A -> B -> Pair A B