Escape special chars in topic and skip mono

[idbrii]

Fix #36.

If the topic contains chars that make markdown formatting difficult ([ ] `), escape them and omit fixed width styling.

Markdown parsers are often inconsistent, so hopefully simpler markdown is more likely to display properly for more users.

Never deployed, but I've tested the code separately based on some examples from #36. I don't know what actual values pop out of the db for topic -- I've guessed them based on vimhelpbot's responses.

My test code:

import re

tests = [
    {
        "topic": "`]",
        "link": "https://vimhelp.org/motion.txt.html#%60%5D",
        "doc": "motion",
    },
    {
        "topic": ":make",
        "link": "https://neovim.io/doc/user/quickfix.html#%3Amake",
        "doc": "quickfix",
    },
    {
        "topic": "c_CTRL-G",
        "link": "https://vimhelp.org/cmdline.txt.html#c_CTRL-G",
        "doc": "cmdline",
    },
    {
        "topic": "c_CTRL-L",
        "link": "https://vimhelp.org/cmdline.txt.html#c_CTRL-L",
        "doc": "cmdline",
    },
    {
        "topic": "pattern.txt",
        "link": "https://vimhelp.org/pattern.txt.html#pattern.txt",
        "doc": "pattern",
    },
    {
        "topic": "c_CTRL-F",
        "link": "https://vimhelp.org/cmdline.txt.html#c_CTRL-F",
        "doc": "cmdline",
    },
    {
        "topic": "search()",
        "link": "https://vimhelp.org/eval.txt.html#search%28%29",
        "doc": "eval",
    },
    {
        "topic": "c_CTRL-R_CTRL-W",
        "link": "https://vimhelp.org/cmdline.txt.html#c_CTRL-R_CTRL-W",
        "doc": "cmdline",
    },
    {
        "topic": "[I",
        "link": "https://vimhelp.org/tagsrch.txt.html#%5BI",
        "doc": "tagsrch",
    },
    {
        "topic": "[_CTRL-I",
        "link": "https://vimhelp.org/tagsrch.txt.html#%5B_CTRL-I",
        "doc": "tagsrch",
    },
]



for t in tests:
    topic = t["topic"]
    link = t["link"]
    doc = t["doc"]

    text = ""
    escaped, count = re.subn(r"([\[\]`])", r"\\\1", topic)
    if count > 0:
        topic = escaped
        text += "* [{}]({}) in _{}.txt_\n".format(topic, link, doc)
    else:
        text += "* [`{}`]({}) in _{}.txt_\n".format(topic, link, doc)

    print(text)

Which produces results that look okay on old reddit and new reddit:

* [\`\]](https://vimhelp.org/motion.txt.html#%60%5D) in _motion.txt_
* [`:make`](https://neovim.io/doc/user/quickfix.html#%3Amake) in _quickfix.txt_
* [`c_CTRL-G`](https://vimhelp.org/cmdline.txt.html#c_CTRL-G) in _cmdline.txt_
* [`c_CTRL-L`](https://vimhelp.org/cmdline.txt.html#c_CTRL-L) in _cmdline.txt_
* [`pattern.txt`](https://vimhelp.org/pattern.txt.html#pattern.txt) in _pattern.txt_
* [`c_CTRL-F`](https://vimhelp.org/cmdline.txt.html#c_CTRL-F) in _cmdline.txt_
* [`search()`](https://vimhelp.org/eval.txt.html#search%28%29) in _eval.txt_
* [`c_CTRL-R_CTRL-W`](https://vimhelp.org/cmdline.txt.html#c_CTRL-R_CTRL-W) in _cmdline.txt_
* [\[I](https://vimhelp.org/tagsrch.txt.html#%5BI) in _tagsrch.txt_
* [\[_CTRL-I](https://vimhelp.org/tagsrch.txt.html#%5B_CTRL-I) in _tagsrch.txt_

[heraldofsolace]

Looks good. Can you add some tests in test_bot.py?

[idbrii]

I added some tests. I don't have reddit's API auth or whatever else is necessary run it locally so I didn't try running the tests directly. They're a port of my above test.