fastboot: implement fastbootd in twrp

fastbootd is a userspace daemon that runs in the recovery
ramdisk. It allows writing single partitions to the super
partition via fastboot CLI. When TWRP sees the fastboot option
in the misc partition during startup, it will start with
the fastbootd page and fastbootd running. Otherwise it will
run recovery normally.

Change-Id: Id7b12d29ef21dbd5950dc884dd1cd788f25357f0
diff --git a/twrp-functions.hpp b/twrp-functions.hpp
index 2686734..611397e 100755
--- a/twrp-functions.hpp
+++ b/twrp-functions.hpp
@@ -39,9 +39,10 @@
 	rb_system,
 	rb_recovery,
 	rb_poweroff,
-	rb_bootloader,     // May also be fastboot
+	rb_bootloader,
 	rb_download,
 	rb_edl,
+	rb_fastboot
 } RebootCommand;
 
 enum Archive_Type {
@@ -116,6 +117,7 @@
 	static bool Get_Encryption_Policy(fscrypt_encryption_policy &policy, std::string path); // return encryption policy for path
 	static bool Set_Encryption_Policy(std::string path, const fscrypt_encryption_policy &policy); // set encryption policy for path
 	static void List_Mounts();
+	static void Clear_Bootloader_Message();
 
 private:
 	static void Copy_Log(string Source, string Destination);