Add properties for year precision to new time model

[stewardont]

Just like DateInstant, but with precision of a year. Useful when we want to store data about which year something happened.

[uscholdm]

This is related to issue: #340

[rjyounes]

There's extensive discussion in #340, as Michael points out, but I'll just highlight the fact that the concept requested here is of a "calendar year" rather than a YearInstant. The latter can be from March 15, 1920 - March 14, 1921, whereas a calendar year would be 1920 or 1921. A calendar year is a type of YearInstant, probably. The example given for DateInstant is somewhat misleading because it also happens to be calendar day, which is similarly is a type of DateInstant, but there are other DateInstants that are not.

[rjyounes]

The issue is irrelevant due to the new model of times which removes the class TimeInstant - see issue #499

[uscholdm]

Its not irrelevant, it is implemented differently. There would be a new property for year precision in addition to day and millisecond.

M.

[rjyounes]

Good point. However, I thought we decided we only wanted to define those two in gist, and leave others to domain ontologies. It's worth raising again.