Spiralogram, Moving Transform: Add week of year

[janezd]

Issue

Implements #258.

Description of changes

• Add day of week to timeseries.PeriodOptions, which adds it to any widget that uses this list (that is, Spiralogram and Moving Transform)
• Add Day of Week into Spiralogram where it deduces the range from the name
• Fix a wrong tooltip (off by one for day of year/month and week of year)

Includes

• [X] Code changes
• [ ] Tests
• [ ] Documentation

[lanzagar]

I added two commits with

• updates to documentation for week-of-year
• bug fix for tooltip html that could not handle control characters (e.g. "<")

I am merging everything, but you can double check my additions @janezd