Allow restoring to read-only file system

This allows the restoration of firmware or modems on read-only
mounted file systems. If the user is able to make a backup of
these partitions, it would only make sense they be allowed to
restore that backup. The current handling is dangerous in that
it happily wipes, but refuses to restore. :)

Note that it would be preferable to use the backup=emmc flag
instead in most cases, added by change:
https://gerrit.omnirom.org/#/c/17183

Change-Id: I32d47c8928dee61595c15a9db16d3c5b9a6d7183
diff --git a/partitions.hpp b/partitions.hpp
index 90f772c..1d43e04 100644
--- a/partitions.hpp
+++ b/partitions.hpp
@@ -51,8 +51,11 @@
 
 public:
 	bool Is_Mounted();                                                        // Checks mount to see if the partition is currently mounted
+	bool Is_File_System_Writable();                                           // Checks if the root directory of the file system can be written to
 	bool Mount(bool Display_Error);                                           // Mounts the partition if it is not mounted
 	bool UnMount(bool Display_Error);                                         // Unmounts the partition if it is mounted
+	bool ReMount(bool Display_Error);                                         // Remounts the partition
+	bool ReMount_RW(bool Display_Error);                                      // Remounts the partition with read/write access
 	bool Wipe(string New_File_System);                                        // Wipes the partition
 	bool Wipe();                                                              // Wipes the partition
 	bool Wipe_AndSec();                                                       // Wipes android secure