log_line_info

Attached is a patch for tagging log lines produced by backends. It is
not quite ready for application - this is for people to look over and
play with.

For my testing I used the following settings:

log_connections = true
log_disconnections = true
log_line_info = '%T [%P] %U(at)%D(%C:%S) %I line:%L '
log_statement = true
log_hostname = true
log_source_port = true

Comments welcome

(Rod Taylor has suggested adding in escapes for remote host and remote
port. This can be done easily enough - I want to call a halt at some
stage and get the basics of this in. Extending it will then be easy).

cheers

andrew