Previously, SimpleSelectors optionally had Attribute-selector data
as well as their main type. Now, they're either one or the other,
which better matches the spec, and makes parsing and matching more
straightforward.
Adds support for the :active pseudo-class for hyperlinks (<a> tags
only).
Also, since it was very similar to :focus and an element having a
focused state was already implemented, I went ahead and implemented
that pseudo-class too, although I cannot come up with a working
example to validate it.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
