Filter lines starting with hash from /etc/shells and /etc/group

Fixes the useradd completion when these files
contains comment lines
Use -1 instead of 0 for the notifyd token "missing value" sentinel

This matches NOTIFY_TOKEN_INVALID
Stop resetting the color for the character under the cursor

Fixes #1821
Minor commenting and cleanup in screen.cpp
brew completion: update completion

 * Remove unsupported options
 * Add new 'unpack' command
__fish_urlencode: rework to behave properly on BSD/OS X

Work on #68.
__fish_config_interactive: send CWD via escapes in Apple Terminal

Closes #68.
Fix issue where tab completions could ignore command-specific completions

Fixes #1742
Makefile: add pkgconfig file to uninstall target
Add a helpful comment warning of a nonsense result from tok_last
Hack the tokenizer to compress multiple adjacent newlines into one

This slightly reduces the size of parse trees, and is otherwise a
minor optimization
Tweak test runner to set up environment better

Update the test runners so they set up their own environment in
test_util.fish. This simplifies the Makefile and paves the way for
adding utility functions for use in the tests themselves.
Define a common `mktemp` for tests

GNU and BSD `mktemp` handle options differently, and it's a useful
utility for tests. As such, define a common `mktemp` function wrapper
for the test suite.

It might actually be nice to expand this for more flags and support it
globally, but that may result in confusion for any users of BSD mktemp
that expect to be running /bin/mktemp.
grep.fish: don't use GREP_OPTIONS as it is deprecated

Closes #1825.
grep.fish: don't set GREP_COLOR

grep will fall back to the default colors.

Closes #1316.
Update various strings for translation, avoid _ for non-translations

Use __ instead of _ as a placeholder for ignored variables in `read`
statements.
Update English translation
tests/status.in: fix test for locale, fall back to default strings
Revert "tests/status.in: fix test for locale, fall back to default strings"

This reverts commit 3b3fde1c5e5a2525fd4139c3853bfafab877950c.
Disable localizations during tests