Partial vacation days

[coijanovic]

There should be a way to add days that are, e.g., half work and half vacation.

Possible syntax: watson-worktime vacation add 1970-01-01x0.5

[Kingdread]

I like the idea, but maybe we can find a better syntax. vacation add 50% 2023-01-01 would work as well and might play better with ranges.