nimble packages should standardize on a builddirectory for generated files, to keep git status clean
proposal
nimble initshould create a builddir, in addition to what it already creates (src, tests, foo.nimble)
it should also add a .gitignore file with contents:
/build
the default template code it generates should write foo.nim to build/fooinstead of foo; likewise with generated binaries for nim test
benefits
makes git statusclean by default (which is a pain when using posix where binaries have no extension; there are workarounds but they're fragile eg with other files that are (non-nim) source or documentation/config files yet don't contain extensions)