Set default frame size to 640x480

- defalut frame size is 640x480, achieved by:
Qt::scaledToHeight()
cv::resize()
In certain case, the results may be different. For example:
--------------------------------------
|   | 1600x1200(4:3) | 3000x2000(3:2)|
|-------------------------------------
|Qt |  640x480       |  640x426(3:2) |
|------------------------------------
|CV |  640x480       |  640x480(4:3) |
--------------------------------------
We may need to handle this in the future

- update measurementUpdate() to handler both edge and lane marker images