Add option to automatically unmount system before installing ZIP

This adds the option to automatically unmount the system partition
before installing a ZIP-file.
This option is enabled by default, This is usefull on SAR-devices
where system is mounted as system_root and ZIPs (i.e. Magisk)
try to unmount system instead of system_root and fail to install.

Change-Id: Id94ae658964679e23aa7fa137e07edf74ee073df
diff --git a/gui/theme/common/landscape.xml b/gui/theme/common/landscape.xml
index 8244c46..230b72f 100755
--- a/gui/theme/common/landscape.xml
+++ b/gui/theme/common/landscape.xml
@@ -2937,6 +2937,9 @@
 					<condition var1="tw_no_sha2" var2="0"/>
 					<data variable="tw_use_sha2"/>
 				</listitem>
+				<listitem name="{@unmount_sys_install=Unmount System before installing a ZIP}">
+					<data variable="tw_unmount_system"/>
+				</listitem>
 			</listbox>
 
 			<checkbox>
diff --git a/gui/theme/common/languages/en.xml b/gui/theme/common/languages/en.xml
index 4a0ac7f..3769da5 100755
--- a/gui/theme/common/languages/en.xml
+++ b/gui/theme/common/languages/en.xml
@@ -719,5 +719,8 @@
 		<string name="include_kernel_log">Include Kernel Log</string>
 		<string name="sha2_chk">Use SHA2 for hashing</string>
 		<string name="unable_set_boot_slot">Error changing bootloader boot slot to {1}</string>
+		<string name="unmount_sys_install">Unmount System before installing a ZIP</string>
+		<string name="unmount_system">Unmounting System...</string>
+		<string name="unmount_system_err">Failed unmounting System</string>
 	</resources>
 </language>
diff --git a/gui/theme/common/portrait.xml b/gui/theme/common/portrait.xml
index e014cc5..8370414 100755
--- a/gui/theme/common/portrait.xml
+++ b/gui/theme/common/portrait.xml
@@ -3150,6 +3150,9 @@
 					<condition var1="tw_no_sha2" var2="0"/>
 					<data variable="tw_use_sha2"/>
 				</listitem>
+				<listitem name="{@unmount_sys_install=Unmount System before installing a ZIP}">
+					<data variable="tw_unmount_system"/>
+				</listitem>
 			</listbox>
 
 			<button style="main_button_half_height">
diff --git a/gui/theme/common/watch.xml b/gui/theme/common/watch.xml
index f5d3222..05b7bd2 100755
--- a/gui/theme/common/watch.xml
+++ b/gui/theme/common/watch.xml
@@ -3640,6 +3640,9 @@
 					<condition var1="tw_no_sha2" var2="0"/>
 					<data variable="tw_use_sha2"/>
 				</listitem>
+				<listitem name="{@unmount_sys_install=Unmount System before installing a ZIP}">
+					<data variable="tw_unmount_system"/>
+				</listitem>
 			</listbox>
 
 			<action>