Minor improvements in the configuration file

config/grub.config

@@ -22,8 +22,14 @@ set imgdevpath="/dev/disk/by-uuid/$rootuuid"
 set pager=1
 set iso_dir="/ISOs"
 set os_dir="/os_files"
+set theme_path="/MultiOS-USB/themes/MultiOS-USB/theme.txt"
 export dev rootuuid imgdevpath iso_dir os_dir
 
+if [ -e "$theme_path" ]; then
+	set theme="$theme_path"
+	export theme
+fi
+
 if loadfont unicode; then
 	if [ "${grub_platform}" == "efi" ]; then
 		set gfxmode=auto
@@ -43,11 +49,6 @@ if loadfont unicode; then
 	terminal_output gfxterm
 fi
 
-if [ -e "/MultiOS-USB/themes/MultiOS-USB/theme.txt" ]; then
-	set theme="/MultiOS-USB/themes/MultiOS-USB/theme.txt"
-	export theme
-fi
-
 function find_grub_cfg {
 	submenu "Detect and boot from GRUB config file (grub.cfg) -->" {
 		grubcfg_found=false