Fixed month and year calculation by adding +1 for month and +1900 for year.
the tm structure has months starting with 0, while libetpan expects that January starts at 1
Furthermore, the year component is an integer starting from 1900 while libetpan expects a 4 digit year number
Merge pull request #494 from pfennema/master

Fixed month and year calculation by adding +1 for month and +1900 for ye...