compute: default to TAB instead of Whitespace as delimiter
tests: improve portability of mktemp

Five X's fail on OpenBSD.
build: portability: add missing <strings.h> header

bzero() and bcopy() fail to compile on DilOS without it.
tests: improve portability when detecting 'nan'

It's 'nan' on most systems, but 'NaN' on some.
portability: cater to systems without a stable sort
maint: Improve output of 'aws-upload' script
maint: add script to build and test on multiple hosts.
maint: .gitignore few more files
maint: improve instructions in 'tag-new-version' script