Basic cache implementation

Changes:

• Added DisCatSharp namespace and CacheLocation enum to CacheLocation.cs file (reference: CacheLocation.cs)
• Added IDisCatSharpCache interface to IDisCatSharpCache.cs file, including methods for adding, getting, and removing objects from the cache, as well as properties for getting the current size of specific caches and checking if the cache is an official extension (reference: IDisCatSharpCache.cs)