First pass of IndexRowImpl (FDBIndexRow). Get the IndexRow interaface
completed, with an completely useless implementation in FDBIndexRow. Add
an empty test. 

Compiles and runs base tests OK. Not run with the ITs.
Merge remote-tracking branch 'github/master' into IndexRowImpl
Merge trunk to get some type changes. Fix one new broken problem.
Step Closer, Compiles, run a test without failures, but returns wrong
results.

Added a few more interfaces to remove more instances of the
PersisititIndexRow[Buffer] and replace with simple IndexRow. 

Enhance the FBDIndexRow a few steps to allow this to function without
failures, but with bad results.
Add several more missing pices to the FBIndexRow, now it passes all the
operator ITs as well as the base tests
Fix Execute$compareRows() to use the static compare() method rather than
relying upon Row.compareTo() which doesn't use the list of TComparisons.
Remove the compareTo(row,...) override as unneeded, once the
Intersect_Ordered$Execute#compareRows() was fixed.
Minor code duplication cleanup in FDBIndexRow. Add tests to
IndexRowTest.
Implement a WriteIndexRow, slightly different from the FDBIndexRow. This
is used by the code writing IndexRows (not regular rows). This used to
be part of the PersititIndexRow[Buffer] code but is really doing two
different things. 

Removed methods from the IndexRow used only for the write portion. 
Update several sections doing index writes to use the new WriteIndexRow.
Remove dead code.
Remove more dead code from the PersistitIndexRowBuffer, as this has been
moved to WriteIndexRow. 

Fix spelling in comment for Row
merge tjoneslo: Write index row impl

Merge pull request #1482 from tjoneslo/sql-layer/WriteIndexRow-impl
https://github.com/FoundationDB/sql-layer/pull/1482