Rebase of pystencils Type System

Fixes #20 (closed)

Complex numbers are not supported anymore

changed milestone to %Release 1.0

added API Update feature ready-for-review refactor labels

requested review from @hoenig

assigned to @holzer

enabled an automatic merge when the pipeline for 65c7e576 succeeds

mentioned in merge request !275 (closed)

mentioned in issue #54 (closed)

mentioned in issue #56 (closed)

merged

mentioned in commit 46ff7269

mentioned in merge request !293 (merged)

mentioned in merge request !294 (merged)

mentioned in merge request !295 (merged)

mentioned in issue #64 (closed)