doctor: ignore internal HOMEBREW_REPOSITORY const

...constant. Instead extract it from the brew CLI, and consider
removing it from our doctor output entirely.
doctor: ignore internal HOMEBREW_CELLAR constant

Instead extract it from the brew CLI, and consider
removing it from our doctor output entirely.
doctor: ignore internal HOMEBREW_VERSION constant

Instead extract it from the brew CLI, and consider
removing it from our doctor output entirely.
make `render_load_path` understand homebrew-fork

tweak doctor's warnings/annotations on `$LOAD_PATH` elements
remove homebrew-fork software_spec.rb

this was required explicitly from Homebrew-cask, but apparently
is not needed
remove cxxstdlib.rb from homebrew-fork

and everything possibly related
remove linux compat from homebrew-fork
remove inreplace.rb from homebrew-fork
remove tap_constants.rb from homebrew-fork
Merge pull request #8226 from rolandwalker/remove_homebrew_cxxstdlib

remove cxxstdlib.rb from homebrew-fork
Merge pull request #8225 from rolandwalker/remove_homebrew_software_spec

remove homebrew-fork software_spec.rb
Merge pull request #8221 from rolandwalker/honest_doctor_homebrew

Adjust `brew cask doctor` for homebrew-fork
remove several homebrew-fork files

* blacklist.rb
* build_environment.rb
* caveats.rb
* cleaner.rb
* language/go.rb
* language/haskell.rb
* language/python.rb
* tab.rb
remove utf-8 encoding cookie
remove homebrew-fork compat.rb and compat dir
Update idisplay license from unknown to gratis

Gratis application, requires purchase of other software to be useful
Refs #8169 and #8213
Update notifyr license from unknown to gratis

Gratis application, requires purchase of other software to be useful
Refs #8169 and #8213
Update nike-plus-connect license from unknown to gratis

Gratis application, requires purchase of hardware to be useful
Refs #8169 and #8213
Update doxie license from unknown to gratis

Gratis application, requires purchase of hardware to be useful
Refs #8169 and #8213
Update dropbox license from unknown to gratis

Gratis application, subscription-based services if desired
Refs #8169 and #8213