fix range typo
Merge pull request #2494 from jw2013/typo

fix typo in range moduledoc
Always return ok from tracking functions
Return explicit :ok from more functions
Ensure case wrapper in cond gets the proper line
throws error for missing docs in DocTest

Signed-off-by: José Valim <jose.valim@plataformatec.com.br>
Add test cases for ExUnit.DocTest failures
Fix regex compilation and set ucp flags
Check if ANSI escape codes are enabled on IEx's clear, closes #2441