Reviewed all documentation for content and formatting

- Pushed helpers into a subdirectory.
- Re-ordered chapters. Created a "Rendering Views" section with the chapters on
  the `PhpRenderer`, view scripts, and the `ViewEvent`.
- Added info on the upcoming 2.7.0 release with regards to callable helpers.

README.md

@@ -3,10 +3,9 @@
 [![Build Status](https://secure.travis-ci.org/zendframework/zend-view.svg?branch=master)](https://secure.travis-ci.org/zendframework/zend-view)
 [![Coverage Status](https://coveralls.io/repos/zendframework/zend-view/badge.svg?branch=master)](https://coveralls.io/r/zendframework/zend-view?branch=master)
 
-`Zend\View` provides the “View” layer of Zend Framework 2’s MVC system. It is a
+zend-view provides the “View” layer of the Zend Framework MVC system. It is a
 multi-tiered system allowing a variety of mechanisms for extension,
 substitution, and more.
 
-
 - File issues at https://github.com/zendframework/zend-view/issues
-- Documentation is at http://framework.zend.com/manual/current/en/index.html#zend-view
+- Documentation is at https://zendframework.github.io/zend-view/