- unify the "build-..." targets
- enable a debug build by default, to simplify development
- bump vendor/DOtherSide
- avoid DOtherSide checks for docs/tests-specific tools like Doxygen
- switch to an in-place build for DOtherSide
- silence the DOtherSide build when V=0, make it more verbose with V=1
- don't delete checked out submodules in the "clean" target
- update build instructions in the README
- centralise Nim compiler options in a top-level "config.nims" (except
`-d:debug` which needs to be on the command line)
4fe6d9b767