Fixes to original tests

Changes to things in the `test/` directory leftover from psqlodbc. Most of the tests are now passing.

I got stuck for many hours on params-test (see comment at top), which has the query `SELECT 'foo' UNION ALL ?` bound to 'bar', but it keeps returning NULL (psqlodbc correctly returns two rows: 'foo, bar'). I've dug deep in the code. I've left this in as a failing test and will return to investigate, hopefully proposing a fix in another merge request.

Some of the tests were commented out (i.e. removed from the Makefile). They have notes at the top regarding what needs fixing (at some point in time).

Test output looks like:
```
alter-test                     | OK
boolsaschar-test               | OK
catalogfunctions-test          | OK
connect-test                   | OK
cvtnulldate-test               | OK
dataatexecution-test           | OK
info-test                      | OK
insertreturning-test           | OK
multistmt-test                 | OK
params-test                    | FAILED (mismatched output)
prepare-test                   | OK
select-test                    | OK
sqlcolumns-test                | OK
sqlprimarykeys-test            | OK
sqlprocedures-test             | OK
stmthandles-test               | OK
```