turnon / turnoff were calling activate / deactivate on nodes even though
their rules didn't link

Fixes #278, thanks to @darkfeels

Thanks to @Hawk777 for reporting this problem

Before that, command block would crash the server if activated when no
players are online

protection is ignored with protection_bypass_priv

Fixed missing capital letter in "ghoststone"

The files are still available for download in a GitHub release

Closes #265

Escape command block commands for formspec

Disabling LuaJIT for user code enables normal working of debug.sethook() even for loops. The drawback is that that code will run more slowly.

The fourth parameter of string.find indicates whether the second parameter should be interpreted literally (true) or as a pattern (false). Allowing patterns enables DoS attacks, but it's possible to
allow literal matching with little effort, by disallowing the function only if the fourth parameter (plain mode) is not `true`.

fixes #255

prohibited, remove pcall and xpcall, fix global lookup of "jit"
variable, correct error locations

Thanks to @ShadowNinja and @gamemanj for fixing this in #241

Please use the screwdriver if you want to rotate trapdoors.
This reverts commit 417a136c.

and remove debug output

This is a major speedup for large mesecon machines / structures.
Force-loaded areas are stored in a file to be persistent over server
reboots. By default, areas are unloaded after 10 minutes (600s) without
usage, this can be customized with the mesecon.forceload_timeout
setting. Please turn max_forceloaded_blocks up for better performance.

Call mesecon.on_dignode / mesecon.on_placenode to take care of that.

up/down pistons from certain directions

Merge branch 'playerdetector_update' of https://github.com/HybridDog/minetest-mod-mesecons into HybridDog-playerdetector_update

Merge branch 'fix_pistons' of https://github.com/HybridDog/minetest-mod-mesecons into HybridDog-fix_pistons

I've implemented a new door API in minetest_game that
performs all the needed things to assure doors are
properly openend and closed, without mods needing to
know the inner details of what needs to be done.

Mesecons can just fetch a reference to the door object
and call the appropriate open or close method, which
simplifies this code a lot.

For compatibility, this code retains the old code path
and tests whether the new API is available, so this
code remains functional if the new API is not available.

Since the metal trapdoor was only recently added, I added
it to the new API codepath only, it's unlikely to be
present on older versions of minetest_game anyway.

As a benefit from the new door API, there is now
absolutely no more accidental switching closed trapdoors
to open on power off, which could happen with the
old method - since that was just a simple toggle.