Implement checking for filter and method authentication requirement.

Currently no filter items are defined pending confirmation of which
require it.
Fix filter logic to account for alist of properties.

sx-auth-filter-auth now returns a filter that will not require auth for
use when auth not available.

Add a few known auth-required types.
Fix sx-auth--method-p to work correctly when there is no submethod
specified.
Do not actually need to check for no submethods.  Already tested for.
Improve method for returning clean filter.

Logic now verifies `include` if `include`,`exclude`,`base` is used.
Otherwise verify entire filter.
sx-method-call rewritten and associated improvements in sx-request.

Now requires `'sx-auth` to account for authentication.

(sx-method-call) is now defined using `cl-defun` and uses keys rather
than positional arguments.

Authentication logic is performed in `sx-method-call` to ensure commands
are only passed on once they are needed.

When access token is available:
  - Filters will be used as provided
  - Methods will be called
When access token is unavailable:
  - Filters will downgrade to only request object that do not require
    auth.
  - Methods will instead use `sx-request-fallback` and return nil.

If auth is not specified but is required, `sx-method-call` will throw an
error.  If auth is specified as `'warn`, `user-error` will be called.

(sx-request--build-keyword-arguments) has been simplified.  It will
always pass an available access_token (api indicates doing so will use a
user/key quota rather than simply key quota).

(sx-request-make) now performs url retrieval directly.  Query
construction is all performed by `sx-method-call`.
Remove default site specification.  Defaults to nil if not
specified (for network-wide searches).

Remove :warning, drop back to :debug
Uses of `sx-method-call` have been updated to use new format.

sx-question now includes 2 authentication requiring parameters,
`question.upvoted` and `question.downvoted`.  These will only be used if
access token exists.

sx-favorites still uses site-workaround pending #82.
Fix auth settings in calls.  Do not use 'warn in non-interactive commands.
Do not initialize Stack-Mode.

Initializing will retrieve user preferences/authentication.  We do not
need this.
Typo fix.
Properly return a nil entry when falling back

sx-request-make returns a nested list (or vector of lists).  Return
`'(())` to ensure it is an acceptable response.
Merge branch 'master' into sx-method-auth.  Conflicts have been
resolved.

Logic and functions have been kept from the `cl-defun` `sx-method-call`
while docstrings have been updated as per #77 when possible.

Conflicts:
	sx-auth.el
	sx-method.el
	sx-question.el
	sx-request.el
Update docstring to reflect uses of `AUTH`.
Fix docstring/argument list ordering (mistake during merge).

Fix `url-automatic-caching` to use `t` rather than
`sx-request-cache-p` (used in tests only).
Whitespace/indent fixup.
Use `(declare (indent 1)) in `sx-method-call`.
Use `\(` for ( at beginning of line in docstring.
Fix indentation following indent declaration.
Whitespace fixup (spaces not tabs).