Use listbox for device-specific advanced menu items

This patch allows items to have more than one action surrounded
by the <actions> tags like other GUI elements. The patch also
adds new twrp command line options that let you reload the theme
and switch to a specific page from the command line:

adb shell twrp reloadtheme
adb shell twrp changepage=advanced

Change-Id: I838ea380a508be07b9fa617034d1954e116febd6
diff --git a/gui/theme/portrait_mdpi/ui.xml b/gui/theme/portrait_mdpi/ui.xml
index 0196a49..8b91641 100755
--- a/gui/theme/portrait_mdpi/ui.xml
+++ b/gui/theme/portrait_mdpi/ui.xml
@@ -202,6 +202,7 @@
 		<variable name="partitionlist_backup_height" value="312"/>
 		<variable name="listbox_timezone_height" value="306"/>
 		<variable name="listbox_settings_height" value="400"/>
+		<variable name="listbox_advanced_height" value="290"/>
 		<variable name="fastscroll_w" value="10"/>
 		<variable name="fastscroll_linew" value="2"/>
 		<variable name="fastscroll_rectw" value="10"/>