orca2easyspin update

[stestoll]

This PR extends orca2easyspin to be able to read properties for ORCA 3, 4 and 5, either from the main output file or the version-specific property file (binary before 5.0, and text-based 5.0 and later).

Addresses #219 .

• [x] rework structure of orca2easyspin to allow reading multiple file types (main output, property files)
• [x] implement spin system import from text-based property file (ORCA 5.0)
• [x] implement spin system import from main ORCA output file (version independent)
• [x] add tests particularly for ORCA 5.0
• [ ] push ORCA to fix bugs in property file

[stestoll]

for list of remaining ORCA v5 property file issues, see https://github.com/StollLab/EasySpin/issues/230