Remove "method", URI input with "hrefVars"

In the most recent draft, "method" simply controlled whether link
input was placed in the URI (for a value of "get") or in the request
body (for a valued of "post").  While correlating with HTML, this
was both confusing due to "get" and "post" not necessarily indicating
the HTTP methods of the same name, and limiting in that users/clients
could not submit data through both the URI and the request body
at the same time.

This introduces "hrefVars" which provides a schema for user input
matching the "href" URI Template variables.  It removes "method"
and makes "schema" and "encType" unambiguously apply to the request
body in all cases.

Clients should choose when to use the request body submission based
on the rules of the protocol given by the URI scheme and the semantics
indicated by the link relation.

Additionally, the complex and apparently rarely if ever used
preprocessing rules have been removed, and both the resulting and
pre-existing limitations have been documented.  They will be the
subject of work for future drafts.

The meta-schemas have been updated accordingly, and the LDO schema has
been brought over from the web site repo and updated.  Improper
use of "$ref" has been fixed with "allOf".

Author: handrews

hyper-schema.json

@@ -18,7 +18,12 @@
             "properties": {
                 "href": {
                     "description": "a URI template, as defined by RFC 6570, with the addition of the $, ( and ) characters for pre-processing",
-                    "type": "string"
+                    "type": "string",
+                    "format": "uritemplate"
+                },
+                "hrefVars": {
+                    "description": "a schema for validating user input to the URI template, where the input is in the form of a JSON object with property names matching variable names in \"href\"",
+                    "allOf": [ {"$ref": "#"} ]
                 },
                 "rel": {
                     "description": "relation to the target resource of the link",
@@ -96,7 +101,8 @@
 
         "base": {
             "description": "URI Template resolved as for the 'href' keyword in the Link Description Object.  The resulting URI Reference is resolved against the current URI base and sets the new URI base for URI references within the instance.",
-            "type": "string"
+            "type": "string",
+            "format": "uritemplate"
         },
         "links": {
             "type": "array",