Scheme creation

[peterk87]

To help make it more clear what's being changed or added for the scheme creation module, it would be a good idea to have a base branch to merge into so that's why scheme-creation/_base has been created.

• Scheme creation relevant feature or change branches should be named scheme-creation/<name of feature> (e.g. scheme-creation/find-discriminatory-snvs) and a pull request should be opened to merge into scheme-creation/_base instead of development.
• Subtyping specific and scheme creation specific code, tests and test data will be separate (biohansel/subtype vs biohansel/create, tests/subtype vs tests/create, tests/data/subtype vs tests/data/create) unless there is common function in some utility function.
• click will be used instead of argparse
• absolute imports only (e.g. from biohansel.subtype.util import whatever instead of from util import whatever; fully qualified path from biohansel)
• command-line application has been changed from hansel to biohansel to align with the name change from bio_hansel to biohansel and to reduce confusion.

[glabbe]

We have move the scheme creation work to a separate repo for the scheme creation tool BioCanon https://github.com/phac-nml/bioCanon