Fixed searching when "." is specified as path
Merge pull request #4 from ichizok/fix-dot

Fixed searching when "." is specified as path
Added a test that finds hidden dir when specified hidden dir.
Added a test that finds hidden file when specified hidden file.
Use depth variable instead of variables named 'onset' and 'went' becase they are same usages.
Implemented depth option.
Used number of CPU for channel capacity.
Used GoRoutine for file grep.
Updated benchmarks. pt became faster than ag!!