Bug fixes in timetable (issue #248)

Problem: If the start lesson equal to the end lesson, there was no lesson shown

Location: Event.create()
Problem: Got absence by id without filtering by term or school year
Solution: Use run_one of api.py, which filters automatically

- Arrange print icon right
- Add line break for header information in LaTeX
- Show one-hour absences with only one number (e.g. 1.) instead of two (e. g. 1.-1.)
- Add dots to lesson numbers in absences

Update Templates | Update views | update SubRow-class | update generateSubtable-function | update events | make everything work | but it doesn't work. Perhaps @hansegucker can help me

Dev to timetable hints

- Fix bug in smart plan generation

- Skip saturday and sunday in Smart Plan (issue #124)
- Remove link "Alle Pläne" (issue #114)
- Refactoring (remove prints)