allow the use of = to define an enum and 0 value
older parser allows this
```
!enum Enum:
field = 0
```
This commit allows both the use of `=` and `:`.
It also allows the value 0 as the value of an enum.
@@ -24,7 +24,7 @@ subscribe -> APPNAME "->" APPNAME params? attribs? ":"
enum -> "!enum" name=NAME attribs? ":"
(WRAPPED_SHORTCUT| %!InlineCommentIndent(enumeration)) {
- enumeration -> name=NAME ":" DIGITS COMMENT_NO_NL*;
+ enumeration -> name=NAME (":" | "=") value=(DIGITS | "0") COMMENT_NO_NL*;
};
// -------------- Mixin --------------- //
