Random generator

[brccabral]

Right now the random generator is static, but this adds one generator to each cpp file that calls for nc::random. Should it be inline instead?

I have a file mylib.cpp that uses nc::random::rand<float>({5, 10}) and I compile it as a library. and I have another file main.cpp that calls for nc::random::seed((int)time(nullptr)) and uses the library, but I was getting the same random values all the time.

add_library(mylib mylib.cpp)
add_executable(myprogram main.cpp)
target_link_libraries(myprogram mylib)

I tested inline std::mt19937_64 generator_; and now my library does generates different values.

I am not entirely sure if this is a fix, otherwise I would make a PR, but my library only works with inline.