Dirty.php: add comments. Add timeout checking

file.php, load.php, Html2Pdf.php: minor updates.
Dirty.php, QuickFormQuery.php: optional $lockTimeout as parameter during instantiating. Return $lockTimeout where necessary. Otherwise read qfq.config.ini. Refactor process(), acquireDirty(), checkDirtyAndRelease().

QfqForm will autonomously fire an lock `extend` request when the lock expired, but a change `t_c` has been made during the lock period `t_l`. I.e. let `t_{current}` be the current time, an `extend` request is made when

    t_c + t_l > t_{current}

holds.

QfqForm will autonomously fire an lock `extend` request when the lock expired, but a change `t_c` has been made during the lock period `t_l`. I.e. let `t_{current}` be the current time, an `extend` request is made when

    t_c + t_l > t_{current}

holds.

Selenium formtest



See merge request !7