add default connection property, for pq\Result->$autoConvert:
pq\Connection->$defaultAutoConvert
add autp conversion constants:
* pq\Result::CONV_BOOL
* pq\Result::CONV_INT
* pq\Result::CONV_FLOAT
* pq\Result::CONV_SCALAR (includes all previous)
* pq\Result::CONV_ARRAY
* pq\Result::CONV_DATETIME
* pq\Result::CONV_ALL (includes all, default)