Create a build system

[pointlander]

For example, see:
https://github.com/pointlander/peg/blob/master/build.go

The build system should support the targets 'build', 'test', 'generate', and whatever else is useful. 'test' should depend upon 'build' which should depend upon 'generate'. 'go clean -testcache' should automatically be called for 'test'.