[feature request] All caps headings

[kunzaatko]

First of all, thanks for the project! It is super cool!
I think all-caps would be a great filter for some headings. Lots of books use all-caps for subheadings.

[kunzaatko]

@Krasjet I made an attempt, at implementing a full pattern match filter. Details are in the commit message. Can you give me some feedback and tell me whether I am going in the right direction?

[kunzaatko]

TODO:

Filter class:

• Fix the tail problem with matching against the whole pattern and accepting only the first full match
• When we arrive at the end without a match, we should filter the previously accepted spns.

Spec generation:

• Add a field with a pattern to the spec.toml generation in pdfxmeta

Add tests:

• Test whether this could be used as the other filters as the 'main' filter and not just a 'checker'

Add documentation:

• in README.md
• in --help

[Krasjet]

I'll review this some time after next Thursday. Sorry for the delay.

[kunzaatko]

Offcourse 👍. Take your time!