Add command line capabilities

Allows sending openrecoveryscript commands to TWRP via shell.
This may be handy for visually impaired users, for various one
click utilities to drive TWRP commands from a computer, for using
TWRP when a catastrophic hardware failure like a shattered screen
prevents you from being able to use touch, or even on devices like
a TV stick where touch and USB mouse input is unavailable.

This patch also includes a few minor changes to openrecoveryscript
including proper support for rebooting via the script and for
decrypting the device via the command line.

Change-Id: I796ad168efdd2da9c25334ac93d1079daaa7b0bc
diff --git a/gui/gui.h b/gui/gui.h
index a927cf3..8e0371e 100644
--- a/gui/gui.h
+++ b/gui/gui.h
@@ -19,6 +19,8 @@
 #ifndef _GUI_HEADER
 #define _GUI_HEADER
 
+#include <stdio.h>
+
 int gui_console_only();
 int gui_init();
 int gui_loadResources();
@@ -26,6 +28,7 @@
 int gui_startPage(const char* page_name);
 void gui_print(const char *fmt, ...);
 void gui_print_color(const char *color, const char *fmt, ...);
+void gui_set_FILE(FILE* f);
 
 #endif  // _GUI_HEADER