Revert "tpl: Rework to handle both text and HTML templates"

Will have to take another stab at this ...

This reverts commit 5c5efa03d2.

Closes #3260

tpl/tplimpl/templateProvider.go

@@ -1,59 +0,0 @@
-// Copyright 2017-present The Hugo Authors. All rights reserved.
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-// http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package tplimpl
-
-import (
-	"github.com/spf13/hugo/deps"
-)
-
-type TemplateProvider struct{}
-
-var DefaultTemplateProvider *TemplateProvider
-
-// Update updates the Hugo Template System in the provided Deps.
-// with all the additional features, templates & functions
-func (*TemplateProvider) Update(deps *deps.Deps) error {
-
-	newTmpl := newTemplateAdapter(deps)
-	deps.Tmpl = newTmpl
-
-	newTmpl.initFuncs()
-	newTmpl.loadEmbedded()
-
-	if deps.WithTemplate != nil {
-		err := deps.WithTemplate(newTmpl)
-		if err != nil {
-			newTmpl.addError("init", err)
-		}
-
-	}
-
-	newTmpl.MarkReady()
-
-	return nil
-
-}
-
-// Clone clones.
-func (*TemplateProvider) Clone(d *deps.Deps) error {
-
-	t := d.Tmpl.(*templateHandler)
-	clone := t.clone(d)
-
-	d.Tmpl = clone
-
-	clone.MarkReady()
-
-	return nil
-}