Currently in Snap!, angles are in degrees clockwise from north. This is the standard in orienteering, but I have never used this system elsewhere. (I left scratch before angles, but it is the same) All three of those are unusual. Usually, 0 is right, and angles are measured is radians counterclockwise. In the scheme number system, the angle of a complex number is in radians. However, this is inconsistent with the rest of Snap! The blocks that would need changing are the turn blocks, the direction getter and setter, and the trigonometry.
... and before Scratch, it was this way in Logo. So you're fighting 50 years of tradition.
Lots of people want this. We agree in principle, but are reluctant to break everyone's projects, so we'd have to have the angles depend on when your project was written. I have this idea that some time we declare a Flag Day and make all the incompatible changes from Scratch at once, but I think Jens doesn't agree.
You might get CCW from East, but you're unlikely to get radians. What you're likely to get is additional trig functions RADSIN, RADCOS, RADATAN, RADATAN2.
Snap! Independence Day! 
Edit: Sorry, I didn't realize this topic was already a month old, so this reply seems kind of pointless, but oh well.