flowvid v0.3.0

• New output type: Generate .flo files in Middlebury format (see fv.output.flo(...))
• New operator: Display optical flow using a quiver plot over the video (see fv.draw_flow_arrows(...))
• New preset: flow_arrows
• Fixed various errors

Check it out at https://pypi.org/project/flowvid/0.3.0/