fix: Function sequence error with prepared execute, SQLTables, same e…

…xecute. (Lost fix)

This was fixed in 2.1.12 and lost during the Python 3 conversion.

The saved prepared statement was not cleaned up when a SQLTables or similar function was used.
If the next execute used the same SQL, pyodbc did not call SQLPrepare.
(cherry picked from commit 7fdec2f)

Issue 227: Fix Python 2.5 compatability

Issue 178: Fixed compilation issues with 4.6.2

Removed deprecated Row_slice.  The sequence structure changed this from an actual function
pointer to a void pointer.  GCC 4.6.2 would not allow the assignment of Row_slice to void*.
This may not build under 2.5.

Also eliminated a bunch of casts to see if newer GCC would uncover other issues.

Issue 198: Added binaryNull object for binding NULL binary parameters.

Single source base for Python 2 and 3

fix: Function sequence error with prepared execute, SQLTables, same e…

…xecute.

The saved prepared statement was not cleaned up when a SQLTables or similar function was used.
If the next execute used the same SQL, pyodbc did not call SQLPrepare.

Issue 192: Source distribution missing utils/pyodbcconf

Issue 145: cursor.execute leaks parameters

Thanks to luke (see issue) for finding, debugging, and providing a fix.

Preparing code for Python 3 port.

Issue 188:	Segfault when fetching NVARCHAR(MAX) data over 511 bytes

The provided fix suggestion looks correct and I can see how it would crash, but was unable to
reproduce with the unit test.  Probably related to Microsoft vs. FreeTDS differences.