Enabled ',' (comma) in StringWithMacro expression

[airween]

This is another form of #36.

Enabled , (comma) character in some cases (eg. by logdata). With this, the below form is allowed:

logdata:'blocked foo, param_with_underscore=%{TX:1}, value_with_underscore=%{TX:2}'

Perhaps we have to review the allowed arguments type at the actions, I think there are more actions which allow this in the engine(s) than here. And there is an another used solution, eg.

   125      'msg:' msg=MessageValue | ...
   ...
   216  MessageValue: "'" /((\\')|[^\'])*/ "'";

which - may be - we can use.