Create a specific @set for the Gonum project

[Dr-Terrible]

Gonum is a collection of libraries for scientific and numeric computing: https://github.com/gonum

For every gonum's component there should be a proper ebuild:

• Matrix - matrix packages
• Optimize - package for finding the optimum value of functions
• Stat - statistics package
• Plot - a repository for plotting and visualizing data
• Lapack - a lapack implementation for Go
• Blas - a BLAS implementation for Go
• Graph - graph packages for Go
• Diff - a set of tools for computing derivatives of a function
• Floats - operations on slices of floats
• Unit - package for converting between scientific units
• internal - internal routines for the gonum project
• root - algorithms for calculating the zero value of functions
• general - general purpose functions for other gonum repositories