Update .luacheckrc

.luacheckrc

@@ -1,12 +1,15 @@
-max_line_length=280
+max_line_length=555
+max_code_line_length=19484
 -- show the warning/error codes as well
 codes=true
 -- skip showing files with no issues
 quiet=1
 -- skip showing undefined variable usage
 -- there are thousands of warnings here because luacheck is unaware of Wesnoth's
 -- lua environment and has no way to check which have been loaded
-global=false
+globals={"wesnoth","wml","gui","filesystem","unit_test","stringx","mathx","ai"}
+allow_defined=false
+allow_defined_top=true
 -- skip showing unused variables
 unused=false
 -- skip showing warnings about shadowing upvalues and empty if branches