This finally brings PostgreSQL to parity with SQLite and MySQL.
Two tests casting binary data to text were removed since behaviour here
should in fact be undefined
Accountinf for any encoding when retrieving data will be addressed by
a later commit
Three test failures remain, but these are minor and will be resolved
soon. Handling of binary data is also broken, but given that this works
fine with the PDO driver, there is presumably some correct method.
PDO does not adequately inform PostgreSQL of a parameter's type, so type
casts are required. Rather than adding these to each query manually, the
queries are instead processed to add type hints automatically.
Unfortunately the queries are processed rather naively; question-mark
characters in string constants, identifiers, regex patterns, or geometry
operators will break things spectacularly.
