Implement literate code verbs in pomagma.corpus

[fritzo]

The following verbs will be needed:

• reformat: like gofmt for go, clang-format for c++
• extract: extracts code from corpus to send to the analyst
• annotate: annotates markdown files with high-latency analyst results
• suggest: gives real-time feedback from low-latency analyst results
• precommit: runs reformat and annotate on corpus code before each git commit