single/inclusive config option

[alexduryee]

Currently, timewalk will attempt to figure out if a date is a single or range date, and set the date type to single or inclusive correspondingly. However, local practice oftentimes disregards single as a date type in lieu of making all non-bulk dates inclusive.

Single/inclusive should be a config option, since there's no real way to tell beforehand what local practice will be. In addition, a default should be set, but I don't know what that should be right now.