Add printf format checking to printf-style log constructors.

This improves safety by diagnosing format string mismatches under both Clang and GCC.
ofEvents: add constructors to event args. Closes #3312
Merge branch 'master' of github.com:openframeworks/openFrameworks
fix some warnings
Merge pull request #3311 from nneonneo/printf_patch

Add printf format checking to printf-style log constructors.
Merge branch 'master' of https://github.com/openframeworks/openFrameworks.git into rexgo