Fix ]]> escaping in CDATA sections

[Turbo87]

This PR resolves #173 by splitting CDATA sections by the ]]> search string and adding multiple BytesCData events, if necessary.

As mentioned in the linked issue, I've also reported this bug at quick-xml to clarify who's responsibility the escaping is. If the responsibility is on the caller then this PR should fix the issue.

I ran cargo bench a couple of times on master and this branch and it seems like the performance impact is negligible.

Related:

• ]]> in CDATA is not escaped #173
• ]]> in CDATA is not escaped tafia/quick-xml#831

[Turbo87]

tafia/quick-xml#832 should fix the issue on the quick-xml side, but it will still require changes to the rss crate due to the newly introduced BytesCData::escaped() fn that will need to be used instead of BytesCData::new(). once a version of quick-xml with the fix is available I'll adjust this PR to use that instead.

[Turbo87]

once a version of quick-xml with the fix is available I'll adjust this PR to use that instead.

done! :)

[Turbo87]

/cc @andy128k in case you hadn't seen this yet :)

[andy128k]

@Turbo87 The change is released in 2.0.11

[Turbo87]

awesome, thank you!