Added basic code to read vhdl file and convert it to Progen. Also added basic code to convert from Progen to VHDL
Removing VMagicProgenConverter.java because contents have been moved to VhdlToElectronicsConverter
Made addInput, addOutput and addChildEntity of Entity public to support entity addition from outside of project
Changed parent id of entity to a reference to parent entity. Also refactored the Entity's connection manager update to take place through projectConnectionManager itself.
Fixed null pointer exception in DisplayAllEntities