Philip Withnall authored Jan 03, 2014 and Olivier Crête committed Jan 31, 2014

Add various compiler warnings to the different levels of
--enable-compile-warnings. No particular scheme has been used to assign
different warnings to different levels, other than that more critical
ones are typically enabled at lower levels upwards.

All code in libnice except the tests currently compiles with
--enable-compile-warnings=error.