Improve performance by removing parse + type checks that are not needed.
Repair FSharp.AutoComplete.
Fix for #534

Since Mono 3.4 docs are fully formed and need not be wrapped in
<Root>…</Root> as they are now MS based, this was causing the issue.
Fallback processing shows the whole string, which is the huge xml doc.
Added skip for MS attribution element
Added error logging for failures rather than appending to tooltip in
debug mode.
Merge pull request #536 from 7sharp9/master

Fix for #534
Merge pull request #530 from rojepp/fix_529

Improve performance by removing parse + type checks that are not needed.