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.

libtls doesn't seem to return when doing blocking I/O, but libretls does every single time.