Correct (almost) all luacheck warnings

Also includes a few code opimizations:
- Combined mining drill functions
- Shorter alias registration (unused?)
- Add TODOs to address later

.luacheckrc

@@ -1,6 +1,8 @@
 unused_args = false
 allow_defined_top = true
-max_line_length = 999
+max_line_length = 150
+-- Allow shadowed variables (callbacks in callbacks)
+redefined = false
 
 globals = {
     "technic", "minetest",
@@ -32,19 +34,7 @@ read_globals = {
     "craftguide", "i3"
 }
 
-files["concrete/init.lua"].ignore = { "steel_ingot" }
-files["technic/machines/MV/tool_workshop.lua"].ignore = { "pos" }
-files["technic/machines/other/frames.lua"].ignore = { "item_texture", "item_type", "adj", "connected", "" }
-files["technic/machines/register/battery_box.lua"].ignore = { "pos", "tube_upgrade" }
-files["technic/machines/register/cables.lua"].ignore = { "name", "from_below", "p" }
-files["technic/machines/register/common.lua"].ignore = { "result" }
-
-files["technic/machines/register/generator.lua"].ignore = { "node" }
-files["technic/machines/switching_station.lua"].ignore = { "pos1", "tier", "poshash" }
-files["technic/radiation.lua"].ignore = { "LAVA_VISC" }
-files["technic/tools/chainsaw.lua"].ignore = { "pos" }
-files["technic/tools/mining_drill.lua"].ignore = { "mode" }
-files["technic_chests/register.lua"].ignore = { "fs_helpers", "name", "locked_after_place" }
-
-files["technic_cnc/cnc.lua"].ignore = { "multiplier" }
-files["wrench/init.lua"].ignore = { "name", "stack" }
+-- Loop warning
+files["technic/machines/other/frames.lua"].ignore = { "" }
+-- Long lines
+files["technic_cnc/cnc_api.lua"].ignore = { "" }