Can't seem to find what patch it was added in but it's been there since before July. Course it's weird that HT has -0o (always been taught 0 can't be -), less he means between -0.01 and -0.99. 
Anytime you have an object that rotates, your starting point is designated as 0 degrees. Example: Old pintle gun only did a 3/4 turn, so you have 0-270degrees as the possible rotation value, and 271-360/0 as unturnable. You don't start out at 360 then jump to 1 degree. One can't start at a value value for a turnable object in terms of degrees, lest they also presume that a circle is not 360 degrees. IE you start at 0.0000000000001 degrees, well, you now have an infinite number of points not plotted in the circle leading up to the 0.0000000000001 value. So there is a distinct difference between 360/0 and 0.000000000001. 0 is used to notate the starting position, and 360 is used to notate a complete rotation in either direction. Hitech used the 180 numbering system to make it easier (I would assume) to quickly judge your potion in the turret in relation to the GV, much as an X Y graph has it's negative X and positive X.
When speaking of angles in common Geometry, you're right, 0 is not a valid value... a triangle with 2 90 degree angles is in reality 3/4 of a rectangle
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Hope I explained this well. I'm sure I've missed something, but you get the idea. (The day doesn't start at 12:00am/0000, it starts at 12:01am/0001, but we collectively accept the former. Just because a majority believes something right doesn't make it so
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