Improved execution time for each loop (until the image is fully gerated) to less than 5 seconds. Of course, it takes much longer to render the image to the display as well as for calibration.
Implemented possible bugfix for iCalendars as suggested by arustleund in issue#20
Improved algorithm for sleeping until the next update and for counting loops left until calibration.
Some minor changes to improve code readbility
8db4f9ff3a