expireLimited with max uint256 failing

[n00b21337]

Problem

The pattern where we have in PostageStamp

expireLimited(type(uint256).max);

will fail in FOR loop when there is too big a number of potential expires, so far this hasnt been happening as usually there is not that much expiring and there is BREAK in loop, but once number of batches get bigger this will happen and then this expiries will get a bit stuck and transactions for them will fail as there will be hit of gas limits of block in chain.

Solution

We need to get to some reasonable max limit that will be max no matter what