References: #4688.
For forward-compatibility; intentionally left undocumented.
The `license` stanza is not free-form. There is a limited
set of valid symbols, of which the argument must be a member.
(The set will later be documented, and probably needs amendments.)
Version numbers and variants of licenses are intentionally
ommitted. The use-case for `license` is filtering and listing
of Casks. We want to avoid becoming a detailed repository of
application descriptions: that information can be found at the
`homepage` URL.
For forward-compatibility, intentionally undocumented. Currently
works only as a synonym: `depends_on :formula` substitutes for
`depends_on_formula`, which is intended to be removed.
However, this PR also provides additional `depends_on` keys for
future expansion of functionality:
- `:cask`
- `:macos`
- `:arch`
- `:x11`
- `:java`
The symbol names were chosen to match those used in Homebrew Formulae.
References: #4688, #2001
`sha256 :no_check` has been supported syntax for a couple of months,
and now is being transitioned to the preferred syntax, replacing
the `no_checksum` stanza (which will still be supported, but
deprecated)
