rpointer filename will need more digits for years in order to allow years > 9999

[ekluzek]

In the latest code where rpointer files now have the simulation date they are for embedded into the name, there will need to be more digits for years allowed in order to go beyond year 9999. This was something done earlier in #20 if this requirement still holds the digits allowed for years will need to be expanded from 4 to 6.

[ekluzek]

@Katetc is this something that should be fixed? Or do you need to check with CISM folks?