On move support aka jumpdrive compat (#9)

* whitespace and minetest. -> core.

- use same whitespace style throughout and fix some indents.
- change from minetest. to core. namespace.

* Update Readme: Minetest -> Luanti

* add luacheck

* update optional depends

* luacheck cleanups

- unused arguments
- shaddowed vars
- var redeclarations
- some whitespace involved in above lines

* clean close of file after reading

* avoid duplicate code

save some lines and some extra method calls.

* avoid error: "unknown global"

* stray whitespace fixups

* whitespace: switch all files to same indent character

tabs -> spaces

* refactor weird declaration

* whitespace: two stray spaces

...that slipped through the cracks on previous whitespace edit

* fix shaddowing global table

* reduce amount of times transformation string is calculated

* use ipairs feature

or use the faster repeat-until-loop

* cap max amount of layers

fixes #5

* fix #5 make transform history non-global

fixes #5
transformation history was shared by all users and kept growing as it
was never truely reset. Every time a user
used a banner a white background was dumped on top of the
stack making it possible to crash the server through an
overflow to core.serialize() function.

* minimize metadata size

also changed banners.max_transformations to
banners.max_undo_levels and lowered the value substantially.

* add versioning

* add recoverable per player history with saved colour

* rename update_all -> update_preview_inv

since it isn't updating everything, only
the preview and the inventory item

* dynamically update masks

to reflect the currently selected colour.

* banner always exists

even if only "" it exists and there isn't an error.
not adding "" or texture string, causes a non critical error.

* use same function declaration style throughout

* remove set_banner_texture()

only used once and is easy enough to have inline

* preserve player undo-history over joins

player could have timed-out and thus lost their history.
It isn't crucial to remove their history, so let's give
them this feature.

* refactor: reusable transformation string creation

unfortunately the git diff is a bit messy on this one.
Nothing changed with:
- banners.Banner
- banners.Banner:new
- banners.Banner:push_transform
- banners.Banner:pop_transform

content of banners.Banner:get_transform_string was moved
to banners.transform_table_to_string with very few changes

* add transform_string_to_table

allows us to add more features such as:
- clean existing banners to slim down data
- read transforms from items in inventory -> allow players
  to change existing patterns without having to start from
  scratch.

* cleanup old banners when their entities are generated

* read item meta allowing players to edit existing banners

* version bump

* oopsie fixes

* remove stray debug point

* add chatcommand banners_fix

fixes #7
provides a work-around for the engine problem with entities.

* sensitive github luacheck syntax

* version bump

* cleanup: compact node definitions

* adds [jumpdrive] compat

github.com/mt-mods/jumpdrive

closes https://github.com/mt-mods/jumpdrive/issues/90

* also make factions banners jump-able

just for completeness sake

.luacheckrc

@@ -8,5 +8,7 @@ read_globals = {
     "dump",
     "factions",
     "inventory_plus",
+    ["table"] = { fields = { "insert_all" } },
     "unified_inventory",
+    "vector",
 }