New MD API: rename functions from _ext to _ret

The _ext suffix suggests "new arguments", but the new functions have
the same arguments. Use _ret instead, to convey that the difference is
that the new functions return a value.
diff --git a/include/mbedtls/sha1.h b/include/mbedtls/sha1.h
index e18e6ac..57bfea4 100644
--- a/include/mbedtls/sha1.h
+++ b/include/mbedtls/sha1.h
@@ -86,7 +86,7 @@
  *
  * \return         0 if successful
  */
-int mbedtls_sha1_starts_ext( mbedtls_sha1_context *ctx );
+int mbedtls_sha1_starts_ret( mbedtls_sha1_context *ctx );
 
 /**
  * \brief          SHA-1 process buffer
@@ -97,7 +97,7 @@
  *
  * \return         0 if successful
  */
-int mbedtls_sha1_update_ext( mbedtls_sha1_context *ctx,
+int mbedtls_sha1_update_ret( mbedtls_sha1_context *ctx,
                              const unsigned char *input,
                              size_t ilen );
 
@@ -109,7 +109,7 @@
  *
  * \return         0 if successful
  */
-int mbedtls_sha1_finish_ext( mbedtls_sha1_context *ctx,
+int mbedtls_sha1_finish_ret( mbedtls_sha1_context *ctx,
                              unsigned char output[20] );
 
 /**
@@ -132,20 +132,20 @@
 /**
  * \brief          SHA-1 context setup
  *
- * \deprecated     Superseded by mbedtls_sha1_starts_ext() in 2.5.0
+ * \deprecated     Superseded by mbedtls_sha1_starts_ret() in 2.5.0
  *
  * \param ctx      context to be initialized
  */
 MBEDTLS_DEPRECATED static inline void mbedtls_sha1_starts(
                                                 mbedtls_sha1_context *ctx )
 {
-    mbedtls_sha1_starts_ext( ctx );
+    mbedtls_sha1_starts_ret( ctx );
 }
 
 /**
  * \brief          SHA-1 process buffer
  *
- * \deprecated     Superseded by mbedtls_sha1_update_ext() in 2.5.0
+ * \deprecated     Superseded by mbedtls_sha1_update_ret() in 2.5.0
  *
  * \param ctx      SHA-1 context
  * \param input    buffer holding the data
@@ -156,13 +156,13 @@
                                                 const unsigned char *input,
                                                 size_t ilen )
 {
-    mbedtls_sha1_update_ext( ctx, input, ilen );
+    mbedtls_sha1_update_ret( ctx, input, ilen );
 }
 
 /**
  * \brief          SHA-1 final digest
  *
- * \deprecated     Superseded by mbedtls_sha1_finish_ext() in 2.5.0
+ * \deprecated     Superseded by mbedtls_sha1_finish_ret() in 2.5.0
  *
  * \param ctx      SHA-1 context
  * \param output   SHA-1 checksum result
@@ -171,7 +171,7 @@
                                                 mbedtls_sha1_context *ctx,
                                                 unsigned char output[20] )
 {
-    mbedtls_sha1_finish_ext( ctx, output );
+    mbedtls_sha1_finish_ret( ctx, output );
 }
 
 /**
@@ -213,7 +213,7 @@
  *
  * \return         0 if successful
  */
-int mbedtls_sha1_ext( const unsigned char *input,
+int mbedtls_sha1_ret( const unsigned char *input,
                       size_t ilen,
                       unsigned char output[20] );
 
@@ -226,7 +226,7 @@
 /**
  * \brief          Output = SHA-1( input buffer )
  *
- * \deprecated     Superseded by mbedtls_sha1_ext() in 2.5.0
+ * \deprecated     Superseded by mbedtls_sha1_ret() in 2.5.0
  *
  * \param input    buffer holding the data
  * \param ilen     length of the input data
@@ -236,7 +236,7 @@
                                                     size_t ilen,
                                                     unsigned char output[20] )
 {
-    mbedtls_sha1_ext( input, ilen, output );
+    mbedtls_sha1_ret( input, ilen, output );
 }
 
 #undef MBEDTLS_DEPRECATED