Cache all the non-weak dynamic library links for a keg rather than the
result of running `brew linkage`. This means that we correctly handle
changes to e.g. what non-keg files are present on disk.

audit: github notability

bump-formula-pr: improve bad argument handling.

download_strategy: fix bzr --HEAD downloads.

Add superenv for Linux

`bzr` needs `BZR_HOME` set to something that's writable in the sandbox
to be able to write log files.

Fix Tty.width cannot get the real width in certain terminal like emacs shell

Signed-off-by: lukertty <lukertty@gmail.com>

Bump github-pages from 185 to 186 in /docs

bin/brew: add 'COLUMNS' and 'LINES' to env variables

Signed-off-by: lukertty <lukertty@gmail.com>

formula-cookbook: remove gdm

Bumps [github-pages](https://github.com/github/pages-gem) from 185 to 186.
- [Release notes](https://github.com/github/pages-gem/releases)
- [Commits](https://github.com/github/pages-gem/compare/v185...v186

)

Signed-off-by: dependabot[bot] <support@dependabot.com>

cmd/list: add common `ls` options.

We need to manually specify these now so let's add a few that we'd
either previously documented or we've caught being used in the wild and
adjust the documentation accordingly.

virtualenv_create(libexec, "python") results in error upon install

When the line was switched to the more explicit

`virtualenv_create(libexec, "python3")` the package installed with any issues. 

Arguably, I am not as comfortable as I would like with Homebrew's relationship with Python, so maybe this reveals a larger underlying issue or there was a mistake within the original Formula.

The formula is hosted [here](https://github.com/saulpw/homebrew-vd). 

```
Last 15 lines from /Users/anja/Library/Logs/Homebrew/visidata/14.pip:
  Removing source in /private/tmp/pip-req-build-CH6VRn
visidata requires Python '>=3.4' but the running Python is 2.7.10
Exception information:
Traceback (most recent call last):
  File "/usr/local/Cellar/visidata/1.2/libexec/lib/python2.7/site-packages/pip/_internal/basecommand.py", line 228, in main
    status = self.run(options, args)
  File "/usr/local/Cellar/visidata/1.2/libexec/lib/python2.7/site-packages/pip/_internal/commands/install.py", line 291, in run
    resolver.resolve(requirement_set)
  File "/usr/local/Cellar/visidata/1.2/libexec/lib/python2.7/site-packages/pip/_internal/resolve.py", line 103, in resolve
    self._resolve_one(requirement_set, req)
  File "/usr/local/Cellar/visidata/1.2/libexec/lib/python2.7/site-packages/pip/_internal/resolve.py", line 262, in _resolve_one
    check_dist_requires_python(dist)
  File "/usr/local/Cellar/visidata/1.2/libexec/lib/python2.7/site-packages/pip/_internal/utils/packaging.py", line 55, in check_dist_requires_python
    '.'.join(map(str, sys.version_info[:3])),)
UnsupportedPythonVersion: visidata requires Python '>=3.4' but the running Python is 2.7.10
```

Add gtk-mac-integration to gnome_devel_whitelist

Fix tap unavailable error for migrated Cask taps.

Fix ignore file

list.rb: use CLI::Parser and improve handling of flags

Fix comparison with Version::NULL on RHS

brew: Conciser error when run from nonexistent directory

Refactoring

Silence `Parser` compatibility warning.

Fall back to `CaskLoader.load` to get a better error message.

This was accounted for in Version::NULL.<=>, but not in Version#<=>,
so these could only be compared if Version::NULL was the left hand
side.

The check had to go above the check that `other` is a version because
`Version::NULL`'s anonymous class does not inherit from `Version`.
(The type check feels like it's probably a smell, but out of scope).

Fix `rspec` deprecations.