* Update README (Setogit)
 * Generalize SetRootDir for indirect dependencies to load messages (Setogit)
 * Pass language to persistent logging callback (Setogit)
 * Fix a bug in sample code in README (Setogit)
 * Make extract error msg directly actionable (Tetsuo Seto)
 * Empty json shouldn't be created if no msgs are extracted (Tetsuo Seto)
 * Remove extra space in README (Setogit)