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.
Pre-existing: this is rather confusing wording.  Probably "environmental situations" would be better expressed as "context" (since "environment" means so many different things, e.g. what getenv() returns, and this *appears* to be referring to where we are in the call-graph).  The example still leaves the reasonable reader without a reason for not Log()ging enter/leave of functions; it might be better to say:
`don't write "Entering function SetFooInBar()", but rather "Setting foo '%s' in bar '%s' over %d."` to indicate the start of the operation the function packages, with relevant details about its arguments.`