- Add the distinction between the 'bug type' and the 'bug description'

HTMLDiagnostics:
- Output the bug type field as HTML comments

scan-build:
- Use the bug type field instead of the bug description for the HTML table.
- Radar filing now automatically picks up the bug description in the title (addresses <rdar://problem/6265970>)


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@63084 91177308-0d34-0410-b5e6-96231b3b80d8