Sorry, pedantry here that I'm about to fix globally in Homebrew/homebrew: it doesn't really make sense to use `Dependency` in the name here because this is a `Requirement` and a `Dependency` is another, similar internal Homebrew class so this change is a bit less confusing.
Current dependency name will be conficted with the formula name of
homebrew/version/ruby20.rb, in result it will cause following error:
```
$ brew readall
Error: problem in /usr/local/Library/Formula/ruby20.rb
wrong number of arguments (3 for 0..1)
```
Fixes https://github.com/Homebrew/homebrew/issues/38638
* convert existing Cask:: namespace to Hbc::
* move Homebrew-fork code under Hbc::
* move freestanding classes such as Tty and TopologicalHash under Hbc::
* recast HOMEBREW_CASK_ constants as HBC_
* modify our Homebrew Formula for backward compatibility
* devscripts and dev docs
global replace of:
'phinze/homebrew-cask' -> 'caskroom/homebrew-cask'
'phinze/cask' -> 'caskroom/cask'
'phinze/homebrew-testcasks' -> 'caskroom/homebrew-testcasks'
and various other specific places that needed updates
<3 the homebrew-cask community!
we had collision issues with homebrew's 'cask' formula (for the emacs
package manager project).
this keeps the in-project and in-formula visibility of the version
number via the old "namespaced global" strategy that keeps a `Cask`
constant out of view of the formula.
gives project-internal visibility of the version constant for use in
displaying to the user.
the formula now does a targeted require to get the version constant from
the new location.