Bump version number to 6.3.2 (#291)

Bump xtb version number to 6.3.1 (#254)

Add possibility to set numerical accuracy in API (#232)

- also give access to max iterations and electronic temperature
- add possibilities to access wavefunction
- remove initial newline from returned buffer

Patch user input to mopac to ensure gradient printout (#147)

- also warn user that input has been patched

bump version to 6.3.0

bump version to 6.2.2 (#71)

Bugfix: ANC-opt hessian read-in error

Atomlist class (#25)

- introduce atomlist class
- wraps usually used atomic lists
- allows for direct use with list io
- add unit test for all functionalities
- introduced atomlist for user data readin
- replaced IO for lists with atom list class
- replaced wbo fragment printout with atom list based IO

initialized repository from 6.2 release branch