Add SourceField and subclasses, rework Source
#1395
| Job | Run time |
|---|---|
| 1m 49s | |
| 7m 48s | |
| 2m 3s | |
| 2m 31s | |
| 1m 54s | |
| 2m 4s | |
| 2m 52s | |
| 2m 9s | |
| 2m 12s | |
| 1m 44s | |
| 2m 43s | |
| 1m 51s | |
| 4m 23s | |
| 2m 7s | |
| 4m 37s | |
| 3m 16s | |
| 3m 48s | |
| 3m 47s | |
| 53m 38s |