Fixes:
1. Lack of 'safe' on minetest.deserialize usage
2. String sandbox bypass via (""):evil()
3. Loss of upcoming digilines messages on server shutdown
4. LCs failing to show information on some errors
5. Interrupt IDs as infinite data storage

Register both luacontroller and microcontroller variations of detector craft recipes.

* Close vulnerability and optimize digiline_send

`digiline_send` as it previously existed was vulnerable to a
time-of-check-to-time-of-use vulnerability in which a table could be
sent, size-checked, and then modified after the send but before
delivery. This would allow larger tables to be sent. It was also slow
because it called `minetest.serialize`. Fix both of these by
implementing custom message cleanup logic which simultaneously computes
the message’s cost.

* Clean up interaction with Digilines

Use `minetest.global_exists` to avoid an undefined global variable
warning when operating a Luacontroller with Digilines not available. Use
the new `digilines` table in preference to the old `digiline` table.

* Copy received messages

When a Digiline message is received at a Luacontroller, copy it so that
local modifications made by the Luacontroller code will not modify
copies of the table that are being passed to other nodes on the Digiline
network.

Improve the code and add vertical movestones

It wasn't necessary, actually.

Fixes a part of #290.

Cyan, magenta, orange, pink, violet and white.

See #337 for details.

New overheating system that doesn’t use the meta.

* Support detection of multiple players in object detector
* Add distance parameter to node detector
* Fix area protection

* Fix inconsistent insulated mesecon names
* Clarify lightstone names
* Rename meselamp to "Mesecon Lamp"
* Use capitalization "Luacontroller" consistently
* Cleanup / improvements for logic gate naming

It used to be so that you could gain two sticky movestones out of one normal one,
this didn't make much sense.

Fixes #289

Make "on" water turbine animated!

This uses a fairly simple trick: the textures are animated, while the
model is static and has a number of rotated copies of the parts that are
seen to move (four copies of the blades, eight copies of the top/bottom
and their edges).  The opaque parts of the textures then decide which of
those faces' copies are visible in each frame.