Proxy GetSQLError through GetDiagRec...
Fix function signatures and add debug
Properly loop through SQLGetDiagRec
Check handle allocation succeeded
Replace GetSQLDiagRecError with GetSQLError in all instances

What really happened is that I change the name of GetSQLDiagRecError
to GetSQLError and then modfied all calls to GetSQLDiagRecError and
GetSQLError so that they are calling properly. Also, GetSQLError is
now overloaded so that a custom error message can be added to the
error object, or not.
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0.5.13