It's still possible to override this automatic mapping by just adding an entry like application/octet-stream gemini gmi in the `types' block.

add_mime nows allocate dinamically copies of the passed strings, so that we can actually free what we parse from the config file. This matters a lot especially with lengthy `types' block: strings that reach the internal mapping are never free'd, so every manual addition is leaked.

matches found with % grep -R '=[ ]*{' . | fgrep -v const

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.

it also does an overflow check on multiplication, other than being more readable.