BUGFIX: SIGNED_FLOAT matched an int... (Issue #84)

lark/grammars/common.g

@@ -12,7 +12,7 @@ DECIMAL: INT "." INT? | "." INT
 // float = /-?\d+(\.\d+)?([eE][+-]?\d+)?/
 _EXP: ("e"|"E") SIGNED_INT
 FLOAT: INT _EXP | DECIMAL _EXP?
-SIGNED_FLOAT: ["+"|"-"] INT
+SIGNED_FLOAT: ["+"|"-"] FLOAT
 
 NUMBER: FLOAT | INT
 SIGNED_NUMBER: ["+"|"-"] NUMBER