Add EVOware pipetting commands

[Y0dler]

This PR aims to implement pipetting commands (as they can be used in the user interface of the EvoWARE) within worklists, i.e. as advanced worklist commands. This enables some pipetting schemes which are not possible with other worklist commands because it allows more precise control over pipetting and wash steps without interference from any grouping shenanigans.

[michaelosthege]

I'm very much looking forward to this!

I noticed two changes that are not strictly related to the addition of EVO commands:

• Typo correction in the ValueError messages
• Enforcing latin-1 encoding

I think it would be best to do these changes in a separate PR which we can fast-track & merge.

Please add a few basic test cases for the new features. You can run them with pytest -v --cov=robotools --cov-report term-missing robotools/tests.py to get a report on the line coverage. With the -k SomePartOfTheTestCaseName you can filter to run tests matching some pattern which is useful too.

I'm keeping my mouth shut over general refactoring changes that I have in mind. But I'll open new issues about them.

[codecov-commenter]

Codecov Report

Merging #21 (dc73d95) into master (9cb5920) will decrease coverage by 18.32%.
The diff coverage is 27.93%.

@@             Coverage Diff             @@
##           master      #21       +/-   ##
===========================================
- Coverage   97.20%   78.89%   -18.32%     
===========================================
  Files           5        5               
  Lines         715      938      +223     
===========================================
+ Hits          695      740       +45     
- Misses         20      198      +178     

Impacted Files	Coverage Δ
robotools/evotools/__init__.py	65.47% <27.93%> (-32.90%)	⬇️

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[michaelosthege]

LGTM. Let#s take care of remaining ToDos in follow-up PRs.