Remove @nest bits that were inadvertently included.

Author: gkellogg

lib/context.js

@@ -279,12 +279,6 @@ api.createTermDefinition = (activeCtx, localCtx, term, defined) => {
         'contain @id.', 'jsonld.SyntaxError',
         {code: 'invalid reverse property', context: localCtx});
     }
-    if('@nest' in value) {
-      throw new JsonLdError(
-        'Invalid JSON-LD syntax; a @reverse term definition must not ' +
-        'contain @nest.', 'jsonld.SyntaxError',
-        {code: 'invalid reverse property', context: localCtx});
-    }
     const reverse = value['@reverse'];
     if(!_isString(reverse)) {
       throw new JsonLdError(
@@ -460,10 +454,6 @@ api.createTermDefinition = (activeCtx, localCtx, term, defined) => {
     mapping['@language'] = language;
   }
 
-  if('@next' in value) {
-    
-  }
-
   // disallow aliasing @context and @preserve
   const id = mapping['@id'];
   if(id === '@context' || id === '@preserve') {
@@ -829,7 +819,6 @@ api.isKeyword = v => {
   case '@index':
   case '@language':
   case '@list':
-  case '@nest':
   case '@omitDefault':
   case '@preserve':
   case '@requireAll':