WebCL API

This pull request concerns the integration of WebCL platform into XML3D.js (related to: http://forge.fi-ware.eu/plugins/mediawiki/wiki/fiware/index.php/FIWARE.Epic.MiWi.3D-UI.DataflowProcessing.WebCLIntegration). The main goal is to provide methods for utilising WebCL acceleration especially in XFlow architecture. However, the API could be potentially utilised also in other areas such as physics calculations.

* Tested with the current develop branch
* Integrated into XML3D.js build system (tested with normal and min build)

Includes:
* Higher level WebCL API layer for WebCL platform
* Sets of Qunit tests for validating the API and WebCL platform functionality
* Complete JSDoc documentation