Prepare 0.4.2 release (#16)

* doc: Change version string

* [skip ci] doc: transfer changelog to 0.4.2 and reset master changelog

Merge pull request #6 from erjel/formating_summary

Formating summary v0.4.1

Add tag for 0.4.0

Add tag for v0.3.0

Add tag for 0.2.9

Add tag for version 0.2.8 (resolves aleju#218)

Add tag for newest version

Add tag for version 0.2.6

Add tag for version 0.2.5

add tag for newest version