Reduce ambiguity in error message since the field match is by ID, not name
Eliminate an issue where the data provider and loader could both be active at the same time
Fix an error that would cause corrupted serialized items after changing a template that resulted in the field ID of a template field to change (e.g. old "foo" field -> new "foo" field).
Logging improvements

- Added explicit exception logging handling to ILogger
- Stack traces are no longer shown in the console for aggregate exceptions (makes it MUCH easier to see what actually happened)
- Exception data during load and reserialize is now also written to Sitecore logs for later review. Sitecore logs include full stack traces.