Replace the broken `64bit-no-nan-tagging_64bit` and `64bit-no-nan-tagging_32bit` configurations with properly named `release_64bit-no-nan-tagging` and `debug_64bit-no-nan-tagging` across all gmake Makefiles and wren_cli.make files. Add the missing `release_64bit-no-nan-tagging` build target definitions for linux, mac, and bsd platforms. Introduce `.travis.sh` script that runs both nan-tagged and non-nan-tagged debug and release builds, and simplify `.travis.yml` to use the new script with per-os env variables instead of matrix options.