Small typo and use DOI link to the paper.

I'm not saying that modelica.org is going to change the file structure soon but linking to a DOI reference is far more safe :smile:
Fix typo
Merge pull request #4 from tbeu/fix-typo

Fix typo
revert change of "umlaute"
Fix unicode issue by using fail-safe HTML entities

See also #2 discussion.
Merge pull request #5 from dietmarw/patch-2

Fix unicode issue by using fail-safe HTML entities
Merge branch 'master' of https://github.com/oestersoetebier/IdealizedContact

Conflicts:
	README.md
added download link to v0.1.0