Scrape command -m, -e and --field

[Yomguithereal]

Subsumes #763 & #740

• [x] -m
• [x] -e
• [x] Add -s support for -m (related to casanova.inferring_writer enhancements).
• [ ] --field
• [x] Function scraper could read annotations to figure out fieldnames in advance: this cannot really work because type hints generally do not include a list length or dict keys...