Currently it's only possible to trigger page-render debugging through the page number, but when looking at the /Pages tree it's often not immediately obvious what the page number actually is.
However, the /Ref of the page is directly available and it's thus handy to be able to use that one instead to enable page-render debugging.
Instead of having all the code for the new debugger in a single file,
split it into multiple files.
This makes it easier to navigate and maintain the codebase.
It'll be make hacking and fixing bugs in the debugger easier.
