Add a way to disable sequence matching

I'm [writing a specification](https://github.com/fsfe/reuse-docs/pull/133) that needs a very, very, very simple globbing of paths, and I am writing a tool that implements the specification. The globbing needs to: - Always use POSIX paths. - Match zero or more characters with `*`, including `.` at the start of a file, excluding path separators. - Match zero or more characters with `**`, including `.` at the start of a file, including path separators. - Escape characters with `\`. Using `DOTGLOB | FORCEUNIX | GLOBSTAR` in wcmatch, I am like 99% of the way there, which is great! Less work for me, and this library looks amazing. However, wcmatch comes with two more features that I do not need: - `?` matches a single character. - `[seq]` and `[!seq]` matches any character in the sequence. I am not well bothered by `?`—I do not need it, but I can add it to the specification without much fuss. Being able to turn this off would be nice, but it is not needed. `[seq]` is far too feature-rich for me to use, however. I do not want to include this in the specification. But if I do not include this in the specification, then my tool must subsequently not implement this. I have considered using a pre-parser to escape all square brackets, but I figured an upstream-first approach would be helpful. I would love a `NOSEQ` flag that disables the behaviour I do not need. --- Additional context: This is being discussed in [this thread in a PR](https://github.com/fsfe/reuse-docs/pull/133#discussion_r1450629582). Copying my available options from that thread: > 1. Open an issue against wcmatch and plead them to include an option to turn this behaviour off. Or do this ourselves—I can write Python! > 2. Do a bad job of documenting this. See: the referenced code. > 3. Don't document it at all. This isn't great. > 4. Do a good job of documenting this. But: that's a loooot of words spent on a feature _we don't even want_. > 5. Make an attempt at turning this behaviour off downstream. Whenever we see `[` or `]`, escape that character internally in the REUSE tool, and the seq behaviour will never be triggered. Subsequently, we needn't document this. But: this may have unintended consequences, maybe. I'm not sure. The relevant bit of the specification is fairly simple. There is a `REUSE.toml` configuration file that matches path expressions against existing files in a project, and applies metadata to those matched files. For example: ```toml [[annotations]] path = "**/*.md" SPDX-License-Identifier = "CC-BY-4.0" ``` This matches all Markdown files and asserts that they are all licensed under CC-BY-4.0. Super simple, easy peasy, no fancy features needed.