Support ProperContains/ProperIn for Intervals

[cmoesel]

The ProperContains / ProperIn operators are similar to ProperIncludes and ProperIncludedIn. The primary difference is that the former two support relationships between an interval and a point, while the latter two support relationships between two intervals.

Note that despite their names, these operates are invoked in CQL using the same syntax is ProperIncludes/ProperIncludedIn. E.g.

define IntervalProperlyContainsPoint: Interval[1, 5] properly includes 3
define PointProperlyInInterval: 3 properly included in Interval[1, 5]