[PATCH 0 of 2 RFC] tests: another try to asciify output of tsttest

[Yuya Nishihara]

Hi, this patch implements ascii-safe test output. It can be enabled
selectively by " (escape)" tag, like (re) or (glob).

Since the previous patch changed whole outputs escaped, it needs to suppress
escape of some common characters,'\t' or '\\', to avoid annoyane.
But sometimes '\t' will be better to be escaped. 
So I consider to escape all control characters and not to enable it by default.

PATCH2 is sample test case using this feature.

Yuya,