Replace custom MS types with STL types

The types that need replacing:

• msstring - It's a C style fixed string type. Replacing it with std::string isn't advised since it's dynamically allocated. It'll probably be best to make our fix fixed string inherited from std::basic_string or use a library like this that contains a fixed string.
• msvariant - A variant variable that fits a c string, int, or float
• msstring_ref - Type defined as a const char*
• mslist - a linked list list that is used a vector throughout the code as well. Should be replaced with a std::vector or std::list depending on what should be used there.
• string_i - In debug mode, a normal string. In release mode its created within the engine and released each level
• msnew - Should probably be replaced with just new.

This should be done after angelscript is embedded.