ark231

I got the error @Hornobster got and also some warnings which meant functions from `libintl.h` was used without explicit declaration, so I modified the code like the patch below and...

@polluks2 It is a workaround for the compilation error caused by the declaration of the variable `next`.

@ctrlcctrlv There is a contradiction between help message and actual behavior. Help message says the default charset is ASCII [(source code)](https://github.com/ctrlcctrlv/cmatrix/blob/892d0e5e4bdfb8724deade829c156d15740bf5e8/charset.h#L102), but in reality, charset is set to half-width katakana...

Another choice, I hope. I've made this from #112