Add ?!= and other methods to simplify creating comparison properties

[mikem2005]

Currently ?= and =? exist to easily create a property that checks two values.

It would be great if ?!=, ?>, ?>=, ?<, ?<= also existed in the library as my team has written custom methods to make these comparisons.

Any objections to submitting a diff?

[ssanj]

I had to write one of these operators myself recently. Would be nice to have these included. :) 👍