Revamp digest functions

- Hash() has been removed because it was ambiguous, Md5() and Sha0() are proper replacements.
- HMacMd5() and HMacSha1() now share a common implementation handled by the new Internal_HMac() function.
- NewMd() and MdProcess() now support plain hashing (without the key).
- NewMd(), SetMdKey() and MdProcess() now check the OpenSSL functions' return value and in case of failure a debug message is printed along with the error string, if available.
- SetMdKey()'s return value has been changed from void to bool, so that it's possible to know whether the function succeeded or not.
- MdProcess()' return value has been changed from void to UINT (unsigned int) and the function now returns the number of bytes written by HMAC_Final() or EVP_DigestFinal_ex().

src/Cedar/BridgeWin32.c

@@ -1337,7 +1337,7 @@ UINT Win32EthGenIdFromGuid(char *guid)
 	Trim(tmp);
 	StrUpper(tmp);
 
-	HashSha1(hash, tmp, StrLen(tmp));
+	Sha1(hash, tmp, StrLen(tmp));
 
 	Copy(&i, hash, sizeof(UINT));