Add setting for .lua extension (#278)

* Add setting for .lua extension

* Feedback  from SquidDev

* Feedback from dan200

* All requested changes are done

* Better description

* Cleaner check

src/main/resources/assets/computercraft/lua/bios.lua

@@ -817,7 +817,8 @@ end
 settings.set( "shell.allow_startup", true )
 settings.set( "shell.allow_disk_startup", (commands == nil) )
 settings.set( "shell.autocomplete", true )
-settings.set( "edit.autocomplete", true )
+settings.set( "edit.autocomplete", true ) 
+settings.set( "edit.default_extension", "lua" )
 settings.set( "lua.autocomplete", true )
 settings.set( "list.show_hidden", false )
 if term.isColour() then

src/main/resources/assets/computercraft/lua/rom/help/settings.txt

@@ -11,6 +11,7 @@ Default Settings:
 shell.autocomplete - enables auto-completion in the Shell.
 lua.autocomplete - enables auto-completion in the Lua program.
 edit.autocomplete - enables auto-completion in the Edit program.
+edit.default_extension - sets the default file extension for files created with the Edit program
 bios.use_multishell - enables Multishell on Advanced Computers, Turtles, Pocket Computers and Command Computers.
 shell.allow_disk_startup - if a Disk Drive with a Disk inside that has a 'startup' script is attached to a computer, this setting allows to automatically run that script when the computer starts.
 shell.allow_startup - if there is a 'startup' script in a computer's root, this setting allow to automatically run that script when the computer runs.

src/main/resources/assets/computercraft/lua/rom/programs/edit.lua

@@ -15,7 +15,10 @@ end
 
 -- Create .lua files by default
 if not fs.exists( sPath ) and not string.find( sPath, "%." ) then
-	sPath = sPath .. ".lua"
+    local sExtension = settings.get("edit.default_extension", "" )
+    if sExtension ~= "" then
+        sPath = sPath .. "." .. sExtension
+    end
 end
 
 local x,y = 1,1