Version 1.0 release to do list

[harry093]

Before releasing GeodePy v1.0 the following needs to be done:

• [x] Standardise names of Transformation objects, etc. (#129)
• [x] Define reverse transformations (#127)
• [x] Set up GitHub Actions to replace Travis (#130)
• [ ] Define style guide (#128)
• [ ] Standardise doc strings
• [ ] Create a Users' Guide (from doc strings or see Read the Docs) (#131)
• [ ] Full test coverage