Bugfix: Ambiguous first argument

Add parentheses around parameters
Bugfix: Prefix assigned but unused variables with underscores
Bugfix: `*' interpreted as argument prefix
Bugfix: Change private attributes to protected

See http://stackoverflow.com/questions/18308627/why-does-ruby-throw-warnings-for-private-attributes
Bugfix: Instance variable @out_of_bounds_time_format not initialized
Bugfix: Instance variable @started_at not initialized
Bugfix: Remove warnings from uninitialized instance variable
Merge branch 'igrep-less-warnings'