Mir update part 1

[9il]

• GEMV is available now
• GEMM has API changed

[9il]

This is not priority. Matrix inversion is not ready yet

[ljubobratovicrelja]

I have updated gemm API in the code.

Also, I've separated mir.experimental.model.rbf and mir.experimental.ml.rbfann modules - rbf would be nothrow @nogc low-level API (I tried following mir.glas style here), and rbfann would contain artificial neural network model implementation that relies on rbf module.

I cannot start working on Mir PR until we get matrix inversion, but @9il, if you'd like, take a quick look at current state, I could use a rough feedback.

[ljubobratovicrelja]

Also, I'm keeping it single threaded not to involve std.parallelism. I suppose we'll solve this eventually...