Geometric Programming Problems 76'

This is a list of 8 problems (more with the variants) from the paper

```
# Source:
# Problem xx in
# Dembo, Ron S.
# "A set of geometric programming test problems and their solutions."
# Mathematical Programming 10.1 (1976): 192-213.
```

https://link.springer.com/article/10.1007/BF01580667

(this needs to be added to the documentation with xx replaced by the number of the problem).

- [ ] Problem 1A
- [ ] Problem 1B
- [ ] Problem 2
- [ ] Problem 3
- [ ] Problem 4A
- [ ] Problem 4B
- [ ] Problem 4C
- [ ] Problem 5
- [ ] Problem 6
- [ ] Problem 7
- [ ] Problem 8A
- [ ] Problem 8B
- [ ] Problem 8C

I haven't found these problems in CUTEst.