Read track configuration from file

Track parameters are now loaded from config files. The following tracks are implemented:
- *circle*: A circle with different sizes.
- *polygon*: The old polygon generator, with the points stored in the config file. The tracks *zigzag*, *curvy* and *evil* are moved to config files.
- *random*: The old random generator, now all parameters are read from config file. The seed is given from command line.