Use %YEAR% variable in LICENSE_TEMPLATE for QtCreator

QtCreator supports the expansion of a bunch of variables[1].
Using that feature, the current year is now being inserted
automatically into the license header.

[1] http://qt-project.org/doc/qtcreator-3.2/creator-tips.html
Fixes for LLVM3.5 and Ubuntu14.04, new FileTemplateLoader in Twig

* Core: Documentation fixes
* Network: Fixed tests for Ubuntu14.04 support
* Tria: Allow to link against LLVM3.4 and 3.5
* Twig: Added FileTemplateLoader
* Twig: Test-case for TemplateEngines caching