Remove lua api functions marked as deprecated

[S-S-X]

Clean up ItemStack:get_metadata() / ItemStack:set_metadata(metadata) with serialization stuff around them. Used with many tools.

[OgelGames]

There is more depreciated stuff that is used:

• [x] current_name (formspec element) - replace with context
• [ ] minetest.get_perlin(seeddiff, octaves, persistence, spread) - replace with minetest.get_perlin(noiseparams) https://github.com/mt-mods/technic/blob/c58673f2af88dc5c6a4df03443415cdbfa97392a/technic_worldgen/oregen.lua#L157
• [ ] minetest.item_place_object() - replace with minetest.item_place()? https://github.com/mt-mods/technic/blob/c58673f2af88dc5c6a4df03443415cdbfa97392a/technic/machines/other/constructor.lua#L57-L62

[S-S-X]

Also more get_metadata and probably set_metadata counterparts (did not search...). PR #233 changes so much for power tools that I don't want to include these, better to save for another PR:

• [ ] ./technic_chests/digilines.lua: and (not item.metadata or (type(item.metadata) == "string" and stack:get_metadata() == item.metadata))
• [ ] ./technic_chests/inventory.lua: local meta = stack:get_metadata()
• [ ] ./technic/tools/cans.lua: if itemstack:get_metadata() == "" then
• [ ] ./technic/tools/cans.lua: return tonumber(itemstack:get_metadata())