Detect broken molden files from Turbomole and fix

[tovrstra]

Also a mistake in the ordering of Cartesian G functions got fixed.

[tovrstra]

@matt-chan or @FarnazH : it would be great if you could you take a quick look at the changes but I understand that you could be too busy. The changes should be ok. This PR make it possible to load erroneous molden files generated by Turbomole. Two other things were changed as well:

• related: fixed the order of the Cartesian G functions when loaded from a molden file. This was wrong on our code

• unrelated: make testing work again on Travis by not installing breathe>=4.4.,<=4.6.. These versions have a bug that break are doc build. The updated version requirements are also mentioned in the install docs.

Thanks!