Refactor: Split the find_object methods to prep for a larger refactoring.
Close unclosed pre/code tags (#4265).
Do not parse redmine links inside pre/code tags (#1288).
Extract parsing of inline attachments, wiki links and redmine links.
Fixed closing tags in syntax highlighting tests.
Add background color to line numbers of highlighted code.
Replace the hardcoded "CodeRay" css class name for highlighted elements.
Extract CodeRay calls to Redmine::SyntaxHighlighting (#2985).
Reverts r1476 that is no longer needed after r3582.
Do not html escape code that is going to be highlighted (#2985, #3359).
