Add Bytea array handling test without calling NpgsqlCommand.Prepare() method.
Fix extra_float_digit setup for Postgresql below 9.0

Npgsql was sending two commands at the same time to set the extra_float_digits parameter.
The first one with value of 2 and the second one with a value of 3.
The problem is that on postgresql below 9.0, there is no support for value of 3 and then neither
command was being processed letting the parameter with the default value of 0.
Now, Npgsql checks which version it is connected to and sends the correct command accordingly.
Merge pull request #69 from franciscojunior/fix-extra-float-digits-setup

Fix extra_float_digit setup for Postgresql below 9.0
Merge pull request #68 from franciscojunior/add-test-bytea-array-handling

Add Bytea array handling test without calling NpgsqlCommand.Prepare() me...
Bugs, tests

Fix bugs in bytea texr encoder on <= 8.4.
Add tests, make a couple others more rigorous.
Improve variable names for readability.
Merge branch 'master' of https://github.com/franciscojunior/Npgsql2 into backend_encoders
Add a test, and increase rigor on a couple others.
Fix test that claims to Prepare(), to actually Prepare().
Add a test for zero-length bytea.
Fix backend to native bytea hex format decoder to work on zero-length data.
String and bytea text format encoders

Re-write the string and bytea text encoders for readability.
Fix bug from previous commit that caused the encoders to fail against PG <= 8.4.
Escape raw text before UTF encoding, not after; after doesn't work on multi-byte data.