Get rid of memoization in missing dep analyzer.

It was causing more trouble than it was worth.

I will profile the code to see how much worse this makes
things, and find other solutions if needed.

Auditors: pl
Fix broken artifacgt caching for codegen.

Added a bunch of clarifying comments in the code
to prevent future regression.

Auditors: pl
Merge branch 'master' of https://github.com/orsenthil/commons