Silence misc compiler warnings.

Also a few comment typo and whitespace fixes.
Oops, used wrong #ifdef for CC_Copy.

CC_Copy is needed if _HANDLE_ENLIST_IN_DTC_ is used, regardless of
CLEANUP_CONN_BEFORE_ISOLATION. That caused compilation on Windows to fail.
Remove some dead code.
Add test case for using SQLBindParameter with SQLExecDirect.
Handle turning standard_conforming_strings to off in mid-session.

We already watched for a ParameterStatus response indicating that
standard_conforming_strings was turned on, and acted accordingly, but
if it was turned off, we did nothing. Fix that.

Also add a test case for that.
Remove common.o on "make clean"
Add test case for multi-statements.
Add test case for testing the effect of COMMIT/ROLLBACK on cursors.

The behavior differs depending on UseDeclareFetch, so there are two expected
outputs for this.
Fix bug when a statement is executed twice with data-at-execution params.

When a statement with array-bound data-at-execution parameters is executed
twice, the second result set was not returned when UseServerSidePrepare=1.
This was demonstrated by the data-at-execution regression test case.
Change the default for UseServerSidePrepare to 1.

The docs have recommended UseServerSidePrepare=1 for server versions 7.4
onwards, so it seems prudent to change the default so that people don't need
to remember to specify it manually.

With UseServerSidePrepare=1, the "insertreturning" regression test case
behaves better, ie. SQLNumResultCols() correctly returns the number of
columns for an INSERT RETURNING statement, even when called before
SQLExecute(). Hence change the expected output. I'm not 100% if the behavior
with UseServerSidePrepare=0 was even correct, so I'm not adding an
alternative expected output file for it.
Add preliminary release notes for upcoming 9.3 release.

This doesn't cover everything yet, but it's a start.