Detector
--------
* This block is only available if digilines and/or mesecons are loaded.

Detects items or entities within a given radius. Also acts as a
digilines conductor.

Only the owner can dig or access the form of the locked version.

UI

Channel - digilines channel of detector.
Radius - block distance from detector to detect.
Entities - if checked detects entities.
Players - if checked detects players.
Drops - if checked detects drops.
Nodes - if checked detects nodes.

mode:
	All - detects to radius in all directions, including diagonal.
	Forward - detects to radius directly in front of the detector (one block high).
	Up - detects to radius directly above the detector (one block wide).
	Down - detects to radius directly below the detector (one block wide).

Mesecons
	Mesecons power is turned on when something is detected, and turned off
	when nothing is detected.

Digilines messages

"start"
	Start the detector.

"stop"
	Stop the detector.

"radius <n>"
	Set radius of the detector. <n> should be a number from 1 to 5, and is
	trimmed to this range.

"entities <true|false>"
	Set detection of entities on or off.

"players <true|false>"
	Set detection of players on or off.

"drops <true|false>"
	Set detection of drops on or off.

"nodes <true|false>"
	Set detection of nodes on or off.

"mode all"
"mode forward"
"mode up"
"mode down"
	Set the detector's mode.

When items or entities are detected a digilines message is sent with the
detector's channel. A message is sent for each found item/entity. The
message is a table with the following keys:

{
	action = "detect",
	detected = table
}

The detected field is a list of detected items. Each entry is of the form:
{
	type = "<type>", -- will be "entity", "player", "drop" or "node"
	name = "<name>",
	label = "<label>",
	pos = { x = n, y = n, z = n },
	count = <count>,
	hp = <number>,
	height = <number>
}

type
	Will be "entity", "player", "drop" or "node".

name
	For "entity" the registered entity name.
	For "player" the player's name.
	For "drop" the registered item name.
	For "node" the registered item name.

label
	For "entity" the name tag text.
	For "player" the player's name.
	For "drop" the registered item name.
	For "node" the registered item name.

pos
	The relative position of the detected item/entity from the detector,
	facing the direction of the detector.
	+x = right
	-x = left
	+z = forward
	-z = behind
	+y = above
	-y = below

count
	The count of items for a "drop", or 1 for everything else.

hp
	Health points for players and entities. Zero for everything else.

height
	Height for players and entities. Zero for everything else. This is simply
	the top position of the object's collision box.
