Improve performance of WordQuery.
PerfTest normal Query again.
Remove PlainQuery.  It's no faster anymore.
Run tests using 4.5.1
Add comment explaining why testcase is commented out.
Add comment noting tight-coupling of a-vs-an scanner and query
Bump version to 2.2.0; Update README's and nuget package specs.
(minor) whitespace.
Added tag 2.2.0 for changeset 85ed5591e79b