test-lib-main.sh: use say_tap and say_color_tap for TAP output

test-lib-main.sh: use say_tap and say_color_tap for TAP output

Introduce two new functions: say_tap and say_color_tap to output
any TAP-specific lines (other than comments) and alter the code
that output such TAP-specific lines to use them.

If a line is output with say_tap or say_color_tap AND the
"$HARNESS_ACTIVE" variable is non-empty then following new behavior
occurs:

  1) The line is output WITHOUT any color sequences no matter what
  2) The "--quiet" option is IGNORED and the line is always output

Additionally, for lines output using say_color the following new
behavior also occurs again ONLY when "$TEST_HARNESS" is active:

  3) If the first character of the output line is '#' then that
     character ONLY is guaranteed to be output WITHOUT color

These changes make the testing library more correct and easier
to use.

Signed-off-by: Kyle J. McKay <mackyle@gmail.com>