Kalzium is KF5-based

[Andreas Cord-Landwehr]

Hi, the last days I finished the KF5-port of Kalzium and as of now, the master 
branch is finally KF5-based \o/ For me it looks that Kalzium works quite fine 
now, but since my last chemistry class is 17 years go (oh wow...) It would be 
great if people with more chemistry background could have a look.

On the technical side, I discovered several regressions that unfortunately 
were introduced during the port. I tried reviewing the respective commits, but 
since some of them are very hard to read, I might have missed some. Moreover, 
with the switch to Avogadrolibs2, which is a actually rewrite of the Qt4-based 
Avogadro version, there are some big changes for the 3D-molecule viewer.
Hence, there are several good reasons to do some testing there :)

Cheers,
Andreas