Classes of geometry objects

Class Point:
   - delete;
   - formatted representation;
   - addition;
   - subtraction;
   - multiplication by scalar;
   - division by scalar;
   - printing to file;
   - plotting;
   - distance between two points;
   - rotation around X, Y, Z axes;
   - rotation around an arbitrary line;
   - projection on a plane.

Class Vector:
   - delete;
   - formatted representation;
   - addition;
   - subtraction;
   - multiplication;
   - division;
   - plotting;
   - length;
   - unit vector;
   - inverse;
   - dot-product;
   - cross-product;
   - angle between two vectors;
   - angle to plane;
   - projection on plane;
   - intersection / minimum distance between skew vectors;

Class Line:
   - delete;
   - formatted representation;
   - plotting;
   - directional vector;
   - moving;
   - distance to point;
   - projection on plane;
   - intersection / minimum distance between skew lines;
   - point of intersection with plane;

Class Section:
   - under construction;

Class Plane:
   - delete;
   - formatted representation;
   - moving;
   - distance to point;
   - line of intersection of two planes;