unify and recast "Cask name" & "title" as "token"

* "Canonical App Name" becomes "Simplified App Name"
* devscript `cask_namer` renamed to `generate_cask_token`
* doc file `CASK_NAMING_REFERENCE.md` renamed to `cask_token_reference.md`
* DSL uses `"#{token}"` for interpolation instead of `"#{title}"`
* documentation text
* backend code (variables, method, class names)
* error message text
* tests
* code comments
* Cask comments
* emphasize `tags :name`
* doc: use "vendor" consistently instead of "developer"
* doc: many man page argument descriptions were incorrect
* incidental clarifications

Many backend variables similar to `cask_name` or `cask` have
been standardized to `cask_token`, `token`, etc, resolving a long-
standing ambiguity in which variables named `cask` might contain
a Cask instance or a string token.

In many places the docs could be shortened from "Cask name" to
simply "token", which is desirable because we use the term "Cask"
in too many contexts.
Merge pull request #7673 from rolandwalker/name_to_token

unify and recast "Cask name" and "title" as "token"