This is a better version of gg. Initially it grew with flags directly
needed to the specific test cases I wanted to write, so it's ugly to use
but handy for tests.
This is a new and re-thought implementation that it is (hopefully)
easier to use both and "curl-like for gemini" but also for scripts and
tests cases.
One completely new feature is the proxying support with -P to send the
request to the given host.
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.
* add -H for explicit servname (for SNI)
* add -v to print also the request
* misc tweaks: move *flag variables to global scope (initialisation to
0 for free!) and explicit handshake.