Change scale for time in calendar view

[ivira979]

Allow for the timescale (left) to be adjusted from hour increments to 15m, 30m, 45m. Right now the scale shows each row as an hour - this results in time events with longer text, or events with a short duration from having their text truncated. It would be nice to be able to zoom/focus on a narrower block of time (up to a 15 minute period) in some instances.