get rid of "wide" mode completely. It turned out,
that it is very inconvenient for users of Postgres 9.6
and older, to have "\if" blocks – when copy-pasting,
one needs additional manual actions to get rid of those;
added new report, "e1 - extensions" -- shows the list
of extensions installed to the current DB, with current
and available versions, highlighting outdated ones;
in report "0" add "avg temp file size" for convenience
(helpful for tuning "work_mem");
in report "0", fix "devision by zero" error, which appeared
when stats were just reset, until the very first checkpoint;
add .gitignore, with macos' ".DS_Store" file mentioned;
show path to postgresql.conf in report "0";
"s2" report rewritten (better formatting and various improvements)