Support for Time lists in WMS GetCapabilities

[jfbourgon]

GeoTrellis-Server is currently providing information about the available Time dimension of a temporal layer using only a Time interval syntax but the OGC WMS 1.3.0 specifications (Annex D) also allows to display time dimension using a Time list syntax.

For instance, the following Time dimension could be displayed as :

<Dimension default="2014-07-01T12:00Z" units="ISO8601" name="time">2014-07-01T12:00:00Z,2015-07-01T12:00:00Z,2016-07-01T12:00:00Z</Dimension>

instead of only

<Dimension default="2014-07-01T12:00Z" units="ISO8601" name="time">2014-07-01T12:00:00Z/2016-07-01T12:00:00Z</Dimension>

Ideally, the service administrator could have a way to select the preferable syntax.