Implement several missing functions

[potocpav]

I needed those 9 functions for my project. I tried my best to implement them in a way similar to the surrounding code.

[coveralls]

Coverage decreased (-0.4%) to 53.12% when pulling 6714171 on potocpav:master into c163865 on swistakm:master.

[swistakm]

Thanks! This is great PR. I also appreciate all the minor docfixes.

[potocpav]

Was the blocker the decreased coverage? If so, how do I increase it - what does it measure?

[swistakm]

Was the blocker the decreased coverage? If so, how do I increase it - what does it measure?

@potocpav: yes, to some extent.

I wanted to add some examples in the docstrings using the :visual-exampe: directive before merging but didn't find enough time to do so. These are executed during tests (so usually bump the coverage) and also included in Sphinx documentation on the readthedocs site. If you include them and all tests pass I will be able to merge it straight away.

Sorry for forgetting about this MR. I'm almost always busy :(

[potocpav]

Messed up my repo, accidentally pushed stuff there. Either way, this would need to be updated and integrated with other work to be merged, which I might do in another PR. Closing.