fix windows test run
unit test round 2
attempting to fix ccache use on darwin
made ccache optional, no longer pulls clang on darwin build
fixing darwin build from Dockerfile
fixed missing nproc on OSX
updated readme to include regtest example, build examples
fix QT unit tests
made -j get passed down, added build.sh
This contains significant rebase / merge / testing work by Naut
<lbrynaut@protonmail.com>, Anthony Fieroni <bvbfan@abv.bg> and Brannon
King <countprimes@gmail.com>.
