[ci] Include a set of input files for regression testing #63
Description
During the development, a lot of test input files have been created to test a lot of corner cases. I suggest including most of these together with the direct output files to enable regression testing. The output files created by Graphviz might differ with different Graphviz versions, and is therefore not very suited for regression testing, but the .gv and .tsv files could be checked by git diff ../../{examples,tutorial,corner_cases}/*.{gv,tsv} as part of the PR checks.
Originally posted by @Tyler-Ward in #59 (comment):
"I have tested it with the files I used for testing the part numbers and they all generated fine."