Better ANTLR parse error wrong-token error message

[mmatsa]

Here is the current error message:

line 571:0 extraneous input 'rule' expecting {MT_scopes_OPT, ET_scopes_OPT, MT_scope_ZOM, ET_scope_ZOM, ',', ')'} Error(s) while parsing null. Exiting.

Lionel said to add this to an issue. He also says:

this error just say that ‘rule' is unexpected. ANTLR gives the valid tokens, which is of little help
a better way would be to print the token regexes