Commit Briefs
fix various compilation errors
Include gmid.h as first header in every file, as it then includes config.h (that defines _GNU_SOURCE for instance). Fix also a warning about unsigned vs signed const char pointers in openssl.
use recallocarray
it also does an overflow check on multiplication, other than being more readable.
improve mime handling
we still have an hardcoded list, but this implements the API needed to modify the mappings.