Support ? as a bind in emulated prepares

Throw informative error when pdo_parse_param fails

keys need to be null-terminated (how did this not get committed before???)
bind-by-name includes the leading : in the name

iactually support :\w+ as binds

forgotten off the last commit

Tweaks for win32

license/copyright block

handle binding/quoting of queries for drivers with emulated prepares