The test builtin fails silently on negative values

Created by: xTibor

This might trip some users coming from GNU. The GNU implementation supports comparisons with signed values while Ion's test only supports unsigned values and fails silently on signed ones.

Reproduction:

test "-100" -eq "200" && echo true || echo false
test "-100" -ne "200" && echo true || echo false
test "-100" -gt "200" && echo true || echo false
test "-100" -lt "200" && echo true || echo false

Expected behavior:

false
true
false
true

Actual behavior:

true
true
true
true

Build information: rustc -V: rustc 1.23.0-nightly (d6b06c63a 2017-11-09) git rev-parse HEAD: 2f176ebe System: KDE neon 5.11 (Ubuntu 16.04 LTS)