Implement mutation analysis pass

[MattWindsor91]

Per #104, I've decided to split the act of detecting mutations into three stages:

• a toggle-able pass in the analysis stage that, similar to filtering, parses compiler logs to find hit counts for mutants, and attaches them to the compiler analysis;
• a change to the stats dumper so that it can dump those hit counts to stats.json (issue forthcoming);
• a separate observer that performs the rotation aspect (likely implemented tomorrow).

This issue tracks adding:

• a pass to the analyser that extracts hit counts from compiler logs;
• logic that enables this analysis when the machine has a mutation campaign running;
• options to the standalone analyser binary that make itpretty-print hit counts (useful for debugging).