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.