A recent commit broke compilation with Python 3. The original author of
html2text.py is deceased and the fork has increased the number of files
for this "simple" helper.

The html2text.py script in this patch was rewritten and its output
matches with lynx (except for a few newlines around lists). This means
that indentation has been added for headings, paragraphs and lists.
Also, since it was written from scratch, a new license could be chosen
that matches Wireshark.

Since now the in-tree html2text.py script provides nicer output, remove
detection of the alternative programs (elinks, links). lynx/w3m is
somehow still necessary for asciidoc though.

(I also looked into reusing html2text.py for the release notes to
replace asciidoc, but the --format=html output produces different output
(HTML adds a ToC and section numbers). For now still require lynx for
release notes)

Tested with Python 2.6.6, 2.7.9, 3.2.6 and 3.4.3 under LC_ALL=C and
LC_ALL=en_US.UTF-8 on Linux. Tested reading from stdin and file, writing
to file, pipe and tty. Tested with cmake (Ninja) and autotools on Arch
Linux x86_64. Test:

    # For each $PATH per python version, execute (with varying LC_ALL)
    help/faq.py -b | tools/html2text.py /dev/stdin | md5sum
    help/faq.py -b | tools/html2text.py | md5sum
    help/faq.py -b | tools/html2text.py
    help/faq.py -b | tools/html2text.py >/dev/null

Change-Id: I6409450a3e6c8b010ca082251f9db7358b0cc2fd
Reviewed-on: https://code.wireshark.org/review/7779


Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Anders Broman <a.broman58@gmail.com>