Support arbitrary signal length in count_leading_zeros

[tilk]

Currently this function requires power of 2 length.

[piotro888]

• update PriorityEncoder to use more efficient count_leading_zeros instead of m.If loop
• refactor FPURounding to use new count_leading_zeros

[Hazardu]

I will open a PR solving the issue sometime this week.

@Durchbruchswagen would you like the PR to target #741 instead of master branch to also do things like removing nearestpow2 that you had to add there?

[Durchbruchswagen]

I will open a PR solving the issue sometime this week.

@Durchbruchswagen would you like the PR to target #741 instead of master branch to also do things like removing nearestpow2 that you had to add there?

If this isn't too big of an issue for you, then sure, go ahead and target #741.