- Added mulit-level depth parsing.
- Updating usage of HTML doc in page content to be efficient.
- Removed now redundant PageContentTest cases.
- Made some include system fixes based upon testing.
Adds a thin wrapper for DOMDocument to simplify and align usage within
all areas of BookStack.
Also means we move away from old depreacted mb_convert_encoding usage.
Closes#4638
In particular, That around the casing of dangerous values within
attributes. This uses some xpath translation to handle different casing
in contains searching.
Fixes issues thrown in custom HMTL head & page content filtering when
the content is comprised of only a single HTML comment.
Adds tests to cover.
For #2804