Polyosam add features

Added options to
- start first sweep x meter from polygon border
- configure the entry circle radius
- configured the min turn radius

Now the last turn can be a half sweep back or half seep forward if the distance from last turn is less than full sweep distance.

All this modification is made to use this module with more confidence in professional photogrammetry.

why have an extra USE_FULL_CIRCLE define instead of directly using POLY_OSAM_USE_HALF_CIRCLE?