Front-end support for LIMIT ROWS DELETE statements

The first commit you have already seen here on GitHub.  The second completes the ticket by doing error checking, planning the statement, and logging the explained plan:
* The HSQL parser stores the text of the DELETE statement in the VoltXML that it generates
* `DDLCompiler` generates VoltXML from the text of the DELETE statement to verify that the statement is a DELETE that targets the correct table
  * The statement is then saved in the catalog as a child of the Table 
* After `VoltCompiler` compiles stored procedures, it proceeds to compile any DELETE statements designed to help enforce the ROW LIMIT constraint
  * It's at this time that the explained plan is logged.
I'd like to know what the standard says.  I forget exactly (if I ever really knew) how quoted vs. unquoted IDs are handled.  

I started to look at HSQL to see how this stuff all works:
* The scanner will preserve case for quoted identifiers
* The scanner will convert to uppercase all unquoted identifiers
* All comparisons between identifiers is done case-sensitive
This means that identifiers that differ only in case may be considered as distinct (by HSQL) provided at least one of them is quoted.

Anyway, it seems like case-sensitive compare is fine here, so I'll go with that.  More generally I'd like to know what's going on with quoted identifiers, what our current behavior is, and what future plans are--this topic seems to come up pretty often (maybe it's because I bring it up though).