v1.23.7: Hide line numbers on man pages

By default. Press left arrow to get them back. Or use start moar with --no-linenumbers=false.

man starts by checking the terminal width, and then formats man pages to fit that width.

Then, if moar adds line numbers, the rightmost part of the man page will be shifted out of view.

So we try to detect showing man pages, and in that case disable line numbers so that the rightmost part of the page is visible by default.

v1.23.6: Pretend `.tgz` files are gzipped text files

If the archive contains text files, this can let you to read those text files.

Note that this does not imply support for viewing archives. moar is not an archive viewer. If it breaks, you get to keep both pieces.

v1.23.5: Use 24bit colors if COLORTERM says we can

Also print some more environment variables with --help if set, since these affect moar's default behavior:

• TERM
• TERM_PROGRAM
• COLORTERM

v1.23.4: Improve Rio terminal support

Also, on --help, print all *PAGER environment variables. This could help troubleshooting.

v1.23.3: Fix escape codes being printed on the terminal

Before this change, if you ran moar with --quit-if-one-screen and manually set a style using --style, you could sometimes get escape sequences printed on the terminal after moar exited.

In this release, that should not happen any more.

v1.23.2: Try preventing control codes on the terminal

Caused by terminal background color detection code. Give it more time and print it on the alt screen.

v1.23.1: Fix LESS_TERMCAP_xx handling

It was broken in 1.23.0.

v1.23.0: Different default style on bright terminal backgrounds

With this release, moar will check the terminal background color and
pick a different default style if the background is bright.

When viewing 24 bit colored text on a 256 color terminal, color
downsampling will now be somewhat more accurate.

Some CLI usability improvements were done. If the command line is wrong,
moar will now no longer print the full help text. This should make it
more obvious what went wrong.

For people using the LESS_TERMCAP_xx compatibility environment
variables:
* They are now visible in --help output
* They are rendered in --help output if they are valid
* They are highlighted in --help output if they are invalid
* --debug will now include a message if they are invalid

v1.22.3: Fix issue with -quit-if-one-stream

Before this release it didn't work for piped input.

v1.22.2: Render man page headings as GenericHeadings

This makes man pages nicer to read out of the box.

Other minor changes in this release:
* Use 16M color themes when requested, used to be 8 color themes (oops)
* Print less text on bad command lines to make the error message easier
  to find
* Render non-breaking spaces, we used to treat them as non-printable