indent and wrap description text

Description line wrap length can be specified with config file option
"detail-descr-width". The default length is 80.

No ascii art boxing yet but it should be easy to add if needed.

Here's an example how it looks like:
```
Mon Feb 04  10:00  Test meeting.
                     Length: 14:00:00
                     Description:
                   -------------------------------------------------------------
                   - Remember something
                   - Remember otherthing
                   - Lorem ipsum dolor sit amet, consectetur adipisicing elit,
                   sed do eiusmod tempor incididunt ut labore et dolore magna
                   aliqua. Ut enim ad minim veniam, quis nostrud exercitation
                   ullamco laboris nisi ut aliquip ex ea commodo consequat.
                   Duis aute irure dolor in reprehenderit in voluptate velit
                   esse cillum dolore eu fugiat nulla pariatur. Excepteur sint
                   occaecat cupidatat non proident, sunt in culpa qui officia
                   deserunt mollit anim id est laborum.
                   -------------------------------------------------------------
```