only pass port to mysqli_connect when it is set
pref_prefs: remove second argument from the constructor
do not try to calculate icon avg color if GD is not present
Revert "_DISABLE_FLOICON -> _ENABLE_FLOICON"

This reverts commit 7f1113a56ad8e66ce3dd9886b4b11dfc30573c7f.
make logging configurable; add logging to syslog
check if http_response_header is defined
update installer mysqli_connect to only use port if defined