Line-tracking preparation and edge avoidance for Lake-finding

After some tests Line-tracking code was furthermore improved. Now its movement is smoother and more precise

Also we started edge avoiding routine. This routine will work in parallel with lake detection and will help rover to avoid falling down from Mars surface. It is based on detection of different value of light reflection on the edge. If left light sensor detects edge then rover stops and front wheel rotates to the right direction on 90 degrees angle. For right light sensor detection it is vice versa. Separately we will add routine for avoiding plateau using central sensor. The programme is not ideal and on the sharp edges when both sensor detect edge it still needs to be improved.