change a few global Lua variables to be local

Running StepMania with the command line argument of --ExportLuaInformation while the current 5.1's default theme (Lambda) was selected added some seemingly stray Lua variables to the Constants table in ./Docs/Luadoc/Lua.xml.

I spotted them here: http://dguzek.github.io/Lua-For-SM5/LuaAPI#Constants

I'm assuming num, bPreference, and bCategory don't need global scope, so I added the local keyword where appropriate.

Themes/_fallback/Scripts/03 CustomSpeedMods.lua

@@ -70,7 +70,7 @@ end
 -- Parses a speed mod and returns the pair (type, number) or nil if parsing
 -- failed.
 local function CanonicalizeMod(mod)
-	num = tonumber(mod:match("^(%d+.?%d*)[xX]$"))
+	local num = tonumber(mod:match("^(%d+.?%d*)[xX]$"))
 	if num ~= nil then
 		return "x", num
 	end

Themes/default/Scripts/03 Gameplay.lua

@@ -12,11 +12,11 @@ local tNotePositions = {
 }
 
 function GetTapPosition( sType )
-	bCategory = (sType == 'Standard') and 1 or 2
+	local  bCategory = (sType == 'Standard') and 1 or 2
 	-- true: Normal
 	-- false: Lower
-	bPreference = ThemePrefs.Get("NotePosition") and "Normal" or "Lower"
-	tNotePos = tNotePositions[bPreference]
+	local bPreference = ThemePrefs.Get("NotePosition") and "Normal" or "Lower"
+	local tNotePos = tNotePositions[bPreference]
 	return tNotePos[bCategory]
 end
 

Themes/legacy/Scripts/03 Gameplay.lua

@@ -12,11 +12,11 @@ local tNotePositions = {
 }
 
 function GetTapPosition( sType )
-	bCategory = (sType == 'Standard') and 1 or 2
+	local bCategory = (sType == 'Standard') and 1 or 2
 	-- true: Normal
 	-- false: Lower
-	bPreference = ThemePrefs.Get("NotePosition") and "Normal" or "Lower"
-	tNotePos = tNotePositions[bPreference]
+	local bPreference = ThemePrefs.Get("NotePosition") and "Normal" or "Lower"
+	local tNotePos = tNotePositions[bPreference]
 	return tNotePos[bCategory]
 end