Support for microsecond precision in timestamps

[jcristovao]

Hi,

Since around the end of 2011, both MySql and MariaDB support (optional) microsecond precision on timestamps.

However, mysql-simple currently raises an exception if faced with such values.
Here I propose a way to address this. My main doubt is of course the conversion of TimeOfDay. I guess you choosen (in the original code) to use attoparsec for speed reasons, but my parsec-foo is not so great, and the solution proposed does parse this values correctly. However, a better (faster!) approach would be nice :)

[abbradar]

Can we merge this solution? I'll add my own doubts: this probably should somehow check if MySQL version is new enough, or queries will fail on old versions. I can't test, however, and maybe old MySQL just ignores the fractional part, which is the best situation. If not, I think there is nothing better than a CPP #ifdef for now.

Regarding using of parseTime instead of attoparsec -- is this acceptable? If not, I can try to make an attoparsec version.