To render in Git webviews as-is, to make it easier to edit, verify,
and to sync up with curl.
- add options to not build the `.3` man pages:
- autotools: `--disable-docs`
- cmake: `LIBSSH2_BUILD_DOCS=OFF`
- building `.3` man pages requires Perl after this patch.
- drop `mansyntax` and the shell / `grep` / GNU `man` tool requirements with it.
- scripts and most logic were copied from curl.
- add `cd2nroff` from curl, with edits to relax curl-specific checks.
- used `nroff2cd` (from curl) to convert from `.3` to `.md`. Then
manually fixed copyrights, inline function references and a couple
of other things.
Credits-to: Daniel Stenberg
Ref: eefcc1bda4
Ref: https://github.com/curl/curl/pull/12730
Ref: https://github.com/libssh2/www/issues/25#issuecomment-3289431671Closes#1660
Add new `libssh2_session_callback_set2()` API that deprecates
`libssh2_session_callback_set()`.
The new implementation offers the same functionality, but accepts and
returns a generic function pointer (of type `libssh2_cb_generic *`), as
opposed to the old function that used data pointers (`void *`). The new
solution thus avoids data to function (and vice versa) pointer
conversions, which has undefined behaviour in standard C.
About the name: It seems the `*2` suffix was used in the past for
replacement functions for deprecated ones. Let's stick with that.
`*_ex` was preferred for new functions that extend existing ones with
new features.
Closes#1285
