Fix documentation for compatibility with Texinfo 5

The Ikarus/Vicare documentation build is broken with the new 5.x Perl rewrite of Texinfo, now in e.g. Debian unstable or — for me — Arch Linux. The issues include `@item` vs. `@itemx` and `@srfi{}` vs. `@ansrfi{N}` (fixed by using the appropriate command) and `@table` refusing to accept macros as item formatters (alas, only fixed by hardcoding the behaviour of `@table @library`, `@table @meta` and `@table @cfunc` where they were used).