Allow more eventvalues for events

[TD-er]

As requested on the forum

ToDo:

• Allow for N %eventvalueN% (not limited?)
• Replace unavailable event values with some default value (0 ???)

[Micha-he]

#3741

[TD-er]

Thanks, that was indeed the issue I had in mind for the 2nd point.

[tonhuisman]

Replace unavailable event values with some default value (0 ???)

Should probably be a setting (not sure what category it should go into though).
And maybe also add a command to set that default? Like: defaulteventvalue,N

[TD-er]

We can also add a command like "letcheck" (or something with a better name) to not assume default values, but check for special values (also to check for NaN etc)