TimeTable does not assert that first time value is 0

[henrikt-ma]

The TimeTable documentation clearly states that the first time value must be 0. However, there is no corresponding assert in the implementation, and failing to satisfy the requirement leads to array indexing out of bounds, which at best will result in a generic out-of-bounds error message that won't be able to pinpoint the problem. In the worst case, the out-of-bounds isn't detected, and the table produces invalid values without any indication of a problem.

[beutlich]

Resolved by 20fe8c9 in master.