UT_DEBOUNCE — On/off delay filter

Cleans up a noisy contact: a float switch on a choppy surface, a pressure switch
near its setpoint, a bouncing limit switch.

Pins

	Pin	Type	Default	What to wire
in	`In`	BOOL	FALSE	Noisy signal
in	`OnDelay`	TIME	T#100ms	Must be TRUE this long to switch on
in	`OffDelay`	TIME	T#100ms	Must be FALSE this long to switch off
out	`Q`	BOOL		Clean signal
out	`Rising` / `Falling`	BOOL		One scan when `Q` switches
out	`ET`	TIME		How long `In` has held its new state (0 when `Q` agrees with `In`)
out	`Remaining`	TIME		The delay still to run before `Q` follows (0 when `Q` agrees with `In`)

Q switches on once In has been TRUE for OnDelay without a break, and off
once it has been FALSE for OffDelay without a break. Anything shorter is ignored.
A delay of 0 (or a negative one) passes In straight through in the same scan.
A delay changed while timing acts at once: lowering OnDelay below the time
In has already been on switches Q on at the next scan.
Q starts off. An input that is already on at start switches Q on after OnDelay.
While In differs from Q, ET counts up and Remaining counts down, like a
TON's ET and PT - ET: show "float high, pump stops in 3 s" on an HMI. Once Q
follows, or In goes back, both are 0.
In is only seen once per scan, so a change shorter than the task interval may be missed.

For a switch that needs alarms or chatter detection, use UT_DIGITAL_IN.