Deprecation of RMUtil_CreateFormattedString

[Dvir Volk]

Hi all.

Just a small notification: 

The rmutil library had a utility function for formatting redis strings, called RMUtil_CreateFormattedString.

Since the modules API now supports RedisModule_CreateStringPrintf which uses the exact same semantics, and requires one less allocation per call, please do not use the RMUtil function anymore.

If you pull the RedisModulesSDK source code, you'll see that it's been replaced with 

#define RMUtil_CreateFormattedString RedisModule_CreateStringPrintf

Which will keep your code operating and even make it faster, since there are fewer memroy allocations now.