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.
There is little point to list structuring for a single item.  Just fold this into the preceding sentence:
`Currently you should stick to ANSI C (or submit a libcompat patch) for sscanf and scanf.`