- For each option's description, prefer capitalizing and ending with a period.
- Also, prefer lowercasing 'Day' as it appears to be the norm in NAME sections.
The new -S/-s/-d flags allow for manually specifying the time of sunset,
ssunrise in the format of HH:MM, and the transitional animation duration
in seconds, respectively.
This is implemented by sidestepping the calc_sun call in manual mode.
The rest of wlsunset operates as usual.