Get subClock by filtering master according to the pattern:
- skip "skip" ticks
- keep the next "keep" ticks
- then, repeatedly skip repSkip ticks and keep repKeep ticks
For instance, FilteredBy(m, s, 5, 1, 3, 2) will skip the first
5 ticks of "m", then keep its next tick for "s", then skip 3 ticks,
keep 2 ticks, skip 3 ticks, keep 2 ticks and so on.