Add support for updating content in text files

[mheap]

Replace common strings in text files. This code currently updates README.md and matches the following patterns:

• @<old> - For GitHub Actions repos
• <org>/<repo>.svg?branch=<old> - Travis badges

It might be worth switching to this plugin if we edit multiple files to make all the changes in a single commit (and use less API requests)

This relates to #7 - @mathiasbynens are there any other patterns you'd like to ship in this version, or should we ship and add patterns as they come up in the future?

[mathiasbynens]

Ooh, that was quick! Since your patch lays the groundwork for easily adding more patterns in the future, let's just ship this as-is? Up to you :)

Thanks for your work on this project!

[mathiasbynens]

You really want replaceAll here, but it's not yet available in Node.js. :( Then again, maybe just doing a single replacement is good enough for now?

[mheap]

Good catch, fixed!

[mathiasbynens]

The new code is:

        var re = new RegExp(r.from, "g");

It should be something like:

        var re = new RegExp(escapeRegExpPattern(r.from), "g");

Otherwise, for example, any special RegExp characters such as . or ? in the input are not interpreted as the raw characters anymore. As a result the ${owner}/${repo}.svg?branch=${old} replacement currently does not work.

An example escapeRegExpPattern implementation can be found here: https://stackoverflow.com/a/9310752/96656

[mathiasbynens]

Other possible replacements (you'd probably want to do these globally, in all files):

• https://github.com/<org>/<repo>/tree/<old> (example)
• https://github.com/<org>/<repo>/blob/<old> (example)
• https://raw.githubusercontent.com/<org>/<repo>/<old> (example)

I'm sure there's more.