Release 0.2.0

@wessels, this is the merge request linked to your milestone 😉 ! I'm going to wait for !29 (merged) first, but afterwards, this one will be next. I added many file readers and the plot3d functionality, but I have to test it first (thus the WIP: tag). If you have any input or want to test stuff early (much appreciated), you can simply pull the release-0.2.0 branch.

• Needs merging of master after !29 (merged) went through!

Fixes #45 (closed)