Portability part 1 - C99 printf

printf, sprintf, fprintf etc are now all C99 compliant. All except sprintf, which is now signaled as deprecated. This raises a few warnings about sprintf usage in the build. Some I fix with pull requests that will follow. Some others should be fixed by the respective authors.
I didn't convert any of the enterprise and nova sprintf()s. The warning will be shown there. I'm a bit afraid of going through them, maybe the need for more refactoring will come up...

I'll add the ```xsnprintf()``` guideline to the warning.