modify test script to work on travis-ci

build custom ECHO binary for test.sh

somehow it seems travis-ci's version of echo doesn't exit with an error
code if writing to its stdout fails. which I think is retarded, but hey.
unix and all that.

while we're on the subject; vim. has undo trees, doesn't have actual
undo. try this:

<insert mode>
proof of Riemann hypothesis<Ctrl + U>

WOOPS!

you're an editor and you lack a feature even Notepad has. hmm...