User-definable animation duration instead of constant time

jQuery provides names for default animation durations that can be
changed or turned off by the user if he wants. Constant numbers
can't.

This also fixes a comparison that made it impossible to set the
duration to 0.

This patch does not remove or change any animation as long as the
user does not touch the jQuery defaults.

Change-Id: I73a16f871ad79c77374b0c1e1abef39c8c3b6e95
Merge "User-definable animation duration instead of constant time"