Add CRT Warnings & fix them

Add CRT Warnings & fix them

Fixes the many uses of strncpy and strncat to use versions of the functions
which the CRT approves of. This means adding the length of the destination
string as a parameter.

The function loader_platform_combine_path was removed and the single use of
it was replaced with a call to snprinf, which achieves the same goal.

There are a few other functions that the CRT warns about, like fopen and
the wide char version of strcpy. These were also replaced with the 'safe'
functions.