Rewrite gamma_inc_taylor and gamma_inc_asym more concisely
#579
| Job | Run time |
|---|---|
| 1m 11s | |
| 3m 46s | |
| 11m 16s | |
| 2m 31s | |
| 2m 1s | |
| 3m 18s | |
| 3m 21s | |
| 2m 13s | |
| 4m 31s | |
| 7m 3s | |
| 41m 11s |