The trim_trailing_whitespace can affect tokens to the right of the caret
so we need to check the token to the left.

Doc comments should be ordered after completion so they don't have to do a blocking wait to see if completion is active.

In order to insert XML doc comment exterior trivia (e.g. /// or '''), we grab the caret position prior to the new line being inserted into the editor and then perform a bit of analysis afterward using that position. However, if there's a selection in the editor and the caret is at the end of that selection, the position will be in an unexpected place in the syntax tree, causing that bit of analysis to fail. So, in this case (and all cases), we use the start of the selection as the position to perform analysis on since that position will be consistent after the new line is inserted.

Been almost a month since the code formatter was run so this change was
a bit larger than would be expected for a normal (weekly) update.  Diffs
mostly around:

- Whitespace changes
- Missing copyright headers
- Missing visibility modifiers

Fix #409:
Add explicit StringComparison.Ordinal or StringComparison.OrdinalIgnoreCase where it was intended,
or replace single-char string literals with chars literals.
Also, provide InvariantCulture in TryParse where it was intended.