TWRP-ify AOSP code

Pull in most TWRP sources
Stub out partition management code
Make it compile -- probably will not boot
Kind of a mess but have to start somewhere
diff --git a/roots.cpp b/roots.cpp
index ca37cf1..3bd6801 100644
--- a/roots.cpp
+++ b/roots.cpp
@@ -22,8 +22,10 @@
 #include <unistd.h>
 #include <ctype.h>
 
+extern "C" {
 #include "mtdutils/mtdutils.h"
 #include "mtdutils/mounts.h"
+}
 #include "roots.h"
 #include "common.h"
 #include "make_ext4fs.h"