problem with binding ofxCvImage textures

I found myself wanting to pass some ofxCvImage textures into a shader and couldn’t seem to figure out why it wasn’t working. Turns out, unless you call an ofxCvImage-derived class’s draw function, the GL texture never gets updated. Since the bTextureDirty and glchannels are protected, there isn’t really a clean way to do it from outside the class itself.

Perhaps we could move the first chunk of ofxCvImage::draw() that checks if the GL texture needs to be updated into a publicly accessible method so the GL texture can be manually updated without being forced to use the built in ofxCvImage draw method.

-Aaron