Move all output handling from VUT to the individual utilities.
Remove -u (unbuffered output) option.

With proper flushing happening on idle, this option is obsolete.
Export a grouping mode to string array from the API
Give error message on -f filter parse errors for VSC (and varnishstat)
Fix parsing of -f arguments in varnishstat (and vsc)

Removed the comma-separated delimiting of this option parsing, as that
conflicted with comma characters often used in backend names. Use
multiple arguments to have several filters.

Parser honors backslash escapes. This makes it possible to list names
containing '.' (also common with backend names).

Fixes: #957
VarnishNCSA base64 implementation now takes a start and end ptr
Beginnings of new varnishncsa
Varnishncsa updated documentation