Add the new HKeyRow_Default operator.
Hook up to optimizer. Generalize classes a little to share more with SingleIndexScan.
Finish explain support.
Split new interface in two.
Update some test expected results.
Forgot about non-condition columns.
More test updates.
Now some new tests specifically designed for the new feature.
merge MMcM: Add a new operator to make an HKeyRow from expressions

Merge pull request #930 from MMcM/akiban-server/hkey-row-operator
https://github.com/FoundationDB/sql-layer/pull/930