Leftover ANSI color/style sequence in piped output

[joelpurra]

Since #5, there should be no colorization if the output is piped (as in "not a TTY") from rainbow to another command. There still seems to be leftover ANSI escape codes at the end of the output though. See also #128 for forcing colorized output.

Tested using rainbow v2.7.1 on Linux, using hexdump to verify the bytes.

---

Plain echo without rainbow, piped to hexdump.

echo 'abc' | hexdump -c

0000000   a   b   c  \n                                                
0000004

With pipe from rainbow without any color filters, piped to hexdump.

Note the four added "reset" bytes, ESC[0m.

rainbow echo 'abc' | hexdump -c

0000000   a   b   c  \n 033   [   0   m                                
0000008

With pipe from rainbow, with one color filter, piped to hexdump.

Note that the color filter is not applied, as per #5. Colorization can be forced using (the workaround in) #128.

rainbow --red 'b' echo 'abc' | hexdump -c

0000000   a   b   c  \n 033   [   0   m                                
0000008