Full ALPB/GBSA with empirical parameters

[haneug]

Initial implementation of the 'full' ALPB and GBSA solvation models as in xtb.

• implements new flags --alpb-xtb and --gbsa-xtb which employ the corresponding empirical parameters and give the same results as in xtb (for water in water the energy difference is below 10⁻⁸ Eh with GFN2-xTB)
• No support for API yet

Looking forward for your suggestions how to improve this!

To Do:

• [x] implement Gshift
• [ ] fix deviation for GFN1-xTB
• [ ] check other solvents
• [ ] clean up and add tests