Allow expressions that reference no attributes.
Add a expression token element to save a token's source string buffer if necessary (e.g. with date/time). Updated PostGIS to by-pass it's time filter setting in favor of MapServer syntax that's handled in translation - not sure if that's a good idea.
Merge branch 'rfc91-filter-transform' of https://github.com/sdlime/mapserver into rfc91-filter-transform
Revise time handling to follow postgis and add Oracle escaping function. Also remove convex hull and always use sdo_aggr_mbr for extents