added more presets
more heatMap
clean up. added optical flow heatMapDraw function

added this function to flow.cpp in ofxcv

        ofRectangle rect = ofRectangle(x,y,last.getWidth(),last.getHeight());
        ofVec2f offset(rect.x,rect.y);
		ofVec2f scale(rect.width/flow.cols, rect.height/flow.rows);
		int stepSize = 4; //TODO: make class-level parameteric
		for(int y = 0; y < flow.rows; y += stepSize) {
			for(int x = 0; x < flow.cols; x += stepSize) {
                ofPushStyle();
				ofVec2f cur = ofVec2f(x, y) * scale + offset;
                ofVec2f length = getFlowOffset(x, y);
                float scaledHue = ofMap(length.length() ,0, 50, ofFloatColor::blue.getHue(), ofFloatColor::red.getHue());
                ofFloatColor magnitudeColor = ofFloatColor::fromHsb(scaledHue, 128, 128 ) ;
                ofSetColor(magnitudeColor);
				ofLine(cur, getFlowPosition(x, y) * scale + offset);
                ofPopStyle();
			}
		}
    }