Make package psr-4 compliant. Classes autoload with composers autoloader

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### Features
 - PowerPoint97 Reader : Implement Basic Reader - @Progi1984 GH-15 GH-14 GH-4
 - ODPresentation Writer : Ability to set auto shrink text - @Progi1984 GH-28
+- Make package PSR-4 compliant. Autoload classes by composer out of the box - @Djuki GH-41
 
 ### Bugfix
 - PowerPoint2007 Writer : Powerpoint Repair Error in Office 2010 - @Progi1984 GH-39

README.md

@@ -59,7 +59,7 @@ the following lines to your ``composer.json``.
 ```
 
 Alternatively, you can download the latest release from the [releases page](https://github.com/PHPOffice/PHPPowerPoint/releases).
-In this case, you will have to register the autoloader.
+In this case, you will have to register the autoloader. Register autoloading is required only if you do not use composer in your project.
 
 ```php
 require_once 'path/to/PhpPowerpoint/src/PhpPowerpoint/Autoloader.php';

composer.json

@@ -38,6 +38,9 @@
     "autoload": {
         "psr-0": {
             "PHPPowerPoint": "src/"
+        },
+        "psr-4": {
+            "PhpOffice\\PhpPowerpoint\\": "src/PhpPowerpoint/"
         }
     }
 }