Update UML diagram
Merge branch 'master' of https://github.com/couthcommander/linkage into couthcommander-master
Add documentation for Linkage exceptions
Add documentation for Matcher
Remove extra linkage diagram
Fix Matcher documentation
Add documentation for MatchSet
Add documentation for Helpers::Database
Improve database connection creation

- accept a Sequel::Database in the Database helper
- remove `:conn` option for Database helper
- require two seperate option hashes in database-related sets: one for
  connection options, and one for other options
- add documentation for MatchSets::Database and ScoreSets::Database
- update documentation for ResultSets::Database
Fix documentation tags in ImportBuffer
Add documentation for ScoreRecorder