Add message grouping.

[MindScriptAct]

In MUD or RogueLike games repeating messages often grouped. by adding multiplication, and showing it as one line.

this feature is off by dofault, and controlled by amomunt of lines to look back to be grouped:

MvcExpressLogger.groupRepeatingLines:int; (0 by default);

for example:

command Test Command executed
Message do "somthing" send.
command Test Command executed
Message do "somthing" send.
command Test Command executed
Message do "somthing" send.
command Test Command executed
Message do "somthing" send.
Message do "somthingElse" send.
command Test Command executed
Message do "somthing" send.
command Test Command executed
Message do "somthing" send.
command Test Command executed
Message do "somthing" send.

will be grouped to :

4 * command Test Command executed
4 * Message do "somthing" send.
Message do "somthingElse" send.
3 * command Test Command executed
3 * Message do "somthing" send.