Speed up the unassociated definitions report (2.4 s -> 0.3 s).
Clean up some garbage in the LexemDefinitionMap table.
Addresses #328.
Slightly improve the unassociated lexems report (0.7s -> 0.5s).
Addresses #328.
Do not run the ambiguous lexems report by default.
Addresses #328.
Make the "lexems with comments" report instant.
Addresses #328.