Fix: Drawing nothing when points match

• Fixed an issue where drawing would be skipped due to divide-by-zero length calculations (NaN) when two points where given the same coordinates.  Now checks ahead of time and will change the length to `FLT_MIN instead.
• As a result, also now pre-calculating the delta and length of segments 0-3 and 1-2, and storing them in DestImageGenInfo for use later.
	• Also storing the `pointUVs` in DestImageGenInfo now.
	• Updated surfaceSTToTexelUV_bilinearQuad() and surfaceSTToTexelUV_barycentricQuad() to take a DestImageGenInfo arg for direct access to the pre-computed values.
	• ratioAndNearestPointAlongSegment() (formerly ratioAlongSegment()) variations to take pre-computer values, or compute them itself
	◦ New ratioAlongSegment() does what ratioAndNearestPointAlongSegment() does but without the nearestPoint calculations.