Error creating userKernels.hpp file for multiple files

When calling the compiler with multiple input files, it does not write all user kernels in userKernels.hpp. There are two main issues that must be fixed:
1. Operations' numbers must be unique even though multiple files are given as input for the compiler;
2. User kernels are being subscribed, so only the last translated input file will have its kernels succesfully recorded in this file.
