* Jenkins: get rid of macOS warnings
We're linking object files with debug info with ones without it. Perfectly justified, from our point of view, but dsymutil complains verbosely about it, with no switch to silence it.
Tests have been moved to the Makefile and the test binaries are built in
parallel.
The Nim compilation scheme has been moved to a script and adapted to
work with different binaries being built in parallel from the same main
source file (think minimal/mainnet tests).
Jacek Sieka
Ștefan Talpalaru
Zahary Karadjov