A lot of changes...

.. ntag simulation stuff from @marshmellows branch "ntag/sim"
.. hf mf mifare fixes from @pwpivi.
.. hw status command
.. speedtest function from @pwpivi
.. Viking Functionalities,   (not a proper DEMOD, but a start)
.. GetCountUS  better precision from @pwpivi
.. bin2hex,  hex2bin  from @holiman

...
starting with getting the T55x7 CONFIGURATION_BLOCK for different clone situations. Ripped from Adam Lauries RFidler,   nothing working or finished..
...
Started working with the T55x7 read command with password actually performs a write block...  See Issue #136  https://github.com/Proxmark/proxmark3/issues/136    Not solved yet.

...
Started add SHA256..   not working yet..

common/sha256.h

@@ -0,0 +1,142 @@
+/**
+ * \file mbedtls_sha256.h
+ *
+ * \brief SHA-224 and SHA-256 cryptographic hash function
+ *
+ *  Copyright (C) 2006-2014, ARM Limited, All Rights Reserved
+ *
+ *  This file is part of mbed TLS (https://tls.mbed.org)
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+#ifndef MBEDTLS_SHA256_H
+#define MBEDTLS_SHA256_H
+
+#if !defined(MBEDTLS_CONFIG_FILE)
+#include "config.h"
+#else
+#include MBEDTLS_CONFIG_FILE
+#endif
+
+#include <stddef.h>
+#include <stdint.h>
+
+#if !defined(MBEDTLS_SHA256_ALT)
+// Regular implementation
+//
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \brief          SHA-256 context structure
+ */
+typedef struct
+{
+    uint32_t total[2];          /*!< number of bytes processed  */
+    uint32_t state[8];          /*!< intermediate digest state  */
+    unsigned char buffer[64];   /*!< data block being processed */
+    int is224;                  /*!< 0 => SHA-256, else SHA-224 */
+}
+mbedtls_sha256_context;
+
+/**
+ * \brief          Initialize SHA-256 context
+ *
+ * \param ctx      SHA-256 context to be initialized
+ */
+void mbedtls_sha256_init( mbedtls_sha256_context *ctx );
+
+/**
+ * \brief          Clear SHA-256 context
+ *
+ * \param ctx      SHA-256 context to be cleared
+ */
+void mbedtls_sha256_free( mbedtls_sha256_context *ctx );
+
+/**
+ * \brief          Clone (the state of) a SHA-256 context
+ *
+ * \param dst      The destination context
+ * \param src      The context to be cloned
+ */
+void mbedtls_sha256_clone( mbedtls_sha256_context *dst,
+                           const mbedtls_sha256_context *src );
+
+/**
+ * \brief          SHA-256 context setup
+ *
+ * \param ctx      context to be initialized
+ * \param is224    0 = use SHA256, 1 = use SHA224
+ */
+void mbedtls_sha256_starts( mbedtls_sha256_context *ctx, int is224 );
+
+/**
+ * \brief          SHA-256 process buffer
+ *
+ * \param ctx      SHA-256 context
+ * \param input    buffer holding the  data
+ * \param ilen     length of the input data
+ */
+void mbedtls_sha256_update( mbedtls_sha256_context *ctx, const unsigned char *input,
+                    size_t ilen );
+
+/**
+ * \brief          SHA-256 final digest
+ *
+ * \param ctx      SHA-256 context
+ * \param output   SHA-224/256 checksum result
+ */
+void mbedtls_sha256_finish( mbedtls_sha256_context *ctx, unsigned char output[32] );
+
+/* Internal use */
+void mbedtls_sha256_process( mbedtls_sha256_context *ctx, const unsigned char data[64] );
+
+#ifdef __cplusplus
+}
+#endif
+
+#else  /* MBEDTLS_SHA256_ALT */
+#include "sha256_alt.h"
+#endif /* MBEDTLS_SHA256_ALT */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * \brief          Output = SHA-256( input buffer )
+ *
+ * \param input    buffer holding the  data
+ * \param ilen     length of the input data
+ * \param output   SHA-224/256 checksum result
+ * \param is224    0 = use SHA256, 1 = use SHA224
+ */
+void mbedtls_sha256( const unsigned char *input, size_t ilen,
+           unsigned char output[32], int is224 );
+
+/**
+ * \brief          Checkup routine
+ *
+ * \return         0 if successful, or 1 if the test failed
+ */
+int mbedtls_sha256_self_test( int verbose );
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* mbedtls_sha256.h */