Increase size of LuaATC code input forms to 15x12 units

The current size of the code form is rather limiting as it fills only a small part of the screen.
Also adds global constant in init.lua so this can easily adapted in the future

advtrains_luaautomation/active_common.lua

@@ -41,13 +41,13 @@ function ac.getform(pos, meta_p)
 			sel=#envs_asvalues
 		end
 	end
-	local form = "size[10,10]"
+	local form = "size["..atlatc.CODE_FORM_SIZE.."]"
 		.."style[code;font=mono]"
 		.."label[0,-0.1;Environment]"
 		.."dropdown[0,0.3;3;env;"..table.concat(envs_asvalues, ",")..";"..sel.."]"
 		.."button[5,0.2;2,1;save;Save]"
 		.."button[7,0.2;3,1;cle;Clear Local Env.]"
-		.."textarea[0.3,1.5;10,9.5;code;Code;"..minetest.formspec_escape(code).."]"
+		.."textarea[0.3,1.5;"..atlatc.CODE_FORM_SIZE..";code;Code;"..minetest.formspec_escape(code).."]"
 		.."label[0,9.7;"..err.."]"
 	return form
 end

advtrains_luaautomation/chatcmds.lua

@@ -5,13 +5,13 @@ local function get_init_form(env, pname)
 	local err = env.init_err or ""
 	local code = env.init_code or ""
 
-	local form = "size[10,10]"
+	local form = "size["..atlatc.CODE_FORM_SIZE.."]"
 		.."style[code;font=mono]"
 		.."button[0.0,0.2;2.5,1;run;Run Init Code]"
 		.."button[2.5,0.2;2.5,1;cls;Clear S]"
 		.."button[5.0,0.2;2.5,1;save;Save]"
 		.."button[7.5,0.2;2.5,1;del;Delete Env.]"
-		.."textarea[0.3,1.5;10,9.5;code;Environment initialization code;"..minetest.formspec_escape(code).."]"
+		.."textarea[0.3,1.5;"..atlatc.CODE_FORM_SIZE..";code;Environment initialization code;"..minetest.formspec_escape(code).."]"
 		.."label[0.0,9.7;"..err.."]"
 	return form
 end

advtrains_luaautomation/init.lua

@@ -16,6 +16,9 @@ atlatc = { envs = {}}
 
 minetest.register_privilege("atlatc", { description = "Player can place and modify LUA ATC components. Grant with care! Allows to execute bad LUA code.", give_to_singleplayer = false, default= false })
 
+--Size of code input forms in X,Y notation. Must be at least 10x10
+atlatc.CODE_FORM_SIZE = "15,12"
+
 --assertt helper. error if a variable is not of a type
 function assertt(var, typ)
 	if type(var)~=typ then