Changes WEB-INF/errors.jsp to unwrap ServletException before display.
Changes content locking not to use the inefficient and soon to be deprecated tool check stream.
Changes content update to check to see if it's changed in between display and update by others.
Fixes Directory.PathType.REDIRECT not working in multi-site implementations.
Fixes concurrent update detection logic accidentally triggering on save after validation error.
Adds ContentLock class that was left out accidentally in a previous commit.
Changes scheduling for past date not to change the publish date, and instead moves that functionality into ContentTools.