test failure would not be reflected by the exit code of 'make'.

Setting a shell parameter in the left-hand side of a pipe is not visible to
commands after the pipe, because the left-hand side forks.  (That's true both
in 'sh' used by 'make' and in 'zsh' that runs tests/test-highlighting.zsh, at
least on my system.)  Therefore, move the colorizing hook to where it doesn't
interfere with setting the $something_failed (in tests/test-highlighting.zsh)
and $result (in Makefile) parameters.

Fixes zsh-users/zsh-syntax-highlighting#187.
Adds a test for zsh-users/zsh-syntax-highlighting#204.

Color is only added when "make test"'s stdout is a tty.

preview-smaller.png is derived from preview.png by 50% downscaling.

Prior art: 66c18e6b71

Followup to b2ac98b981.

Fixes zsh-users/zsh-syntax-highlighting#217.

Fixes zsh-users/zsh-syntax-highlighting#218.

Update expectations on the subshell test (which triggered this bug, since it has
a passing test point following a 'todo' test point).

Make the test pass by setting explicitly the global state (existing $HOME) it
depends on.  Test another value of the global state (a non-existing $HOME).

That allows tests to be completely independent of each other, so tests that
change global state — such as modify environment variables, define functions or
aliases, or hash commands — will not affect other tests, without needing an
explicit cleanup step.

This enables testing path-tilde-home with and without $HOME set, which is part
of issue #216.

While at it, convert the test harness to TAP.  This fixes issue #180 by adding
support for "not ok 42 # TODO" output.

This commit assumes that 'grep' supports POSIX-compliant -q and -v flags.

Patch-by: Matthew Martin <phy1729@gmail.com>

Fixes zsh-users/zsh-syntax-highlighting#215.

Based on text by Carsten Hey <carsten@debian.org>.

Follow-up to the last commit.

E: zsh-syntax-highlighting: missing-dep-for-interpreter zsh => zsh | zsh-beta (usr/share/zsh-syntax-highlighting/highlighters/main/main-highlighter.zsh)
W: zsh-syntax-highlighting: executable-not-elf-or-script usr/share/zsh-syntax-highlighting/highlighters/main/main-highlighter.zsh

All these files should be sourced, not executed; and Debian's lintian complains:

W: zsh-syntax-highlighting: script-not-executable usr/share/zsh-syntax-highlighting/zsh-syntax-highlighting.zsh

Currently, this only works in installed trees and exported tarballs; the
parameter is left unset when running directly from a git worktree.

Tested with 'bmake -B'.

Found-by: Carsten Hey

Fixes issue #213.

This reverts commit 8e7c26f489.

Currently, after a 'yank', paste highlighting (via $YANK_ACTIVE in zsh 5.1.1)
is applied but other highlighting (e.g., string highlighting when the yanked
text is «"foo» as a new word) is not.

See issue #183 for context.

Conflicts:
	zsh-syntax-highlighting.zsh

As explained in #143 (which was a PR for #99), 'yank-pop' only works when the
previous widget has the ZLE_YANK flag, which means wrapping the 'yank' widget
breaks the 'yank-pop' widget (makes it a no-op).  However, that is a reason
against wrapping the 'yank' widget, but not against wrapping the 'yank-pop'
widget.  Indeed, if 'yank-pop' is wrapped but 'yank' isn't, then yank-pop
functions correctly and updates highlighting properly.

To unbreak yank-pop, either 'yank' should be excluded from wrapping, or one of
the fixes mentioned on issue #183 should be applied.

* danielsh/versionstamp:
  versionstamp: Set up '.revision-hash' file.
  versionstamp: Handle NO_FUNCTION_ARGZERO.
  Set the version number.