Issue #13: added composer.json

Added composer.json for dependency/autoloader management instead of hardcoded requires in Autoloader.php
Issue #13: added Composer instructions to README
Issue #5: Properly handle $this
Refactored declared/called function extraction to function PHPDCD_Detector::analyseSourceCode
Added test for issue #18
Issue #18: Initial implementation of detecting calls to a class parent's implementation
Issue #18: Added support for multilevel class hierarchies

Refactored source code analysis to separate class PHPDCD_Analyser, for more flexible/scalable code analysis handling