Added Delete Node and Delete Edge buttons
Merge branch 'test' of https://github.com/SEGroup10/IntelliGraph into test

Conflicts:
	IntelliGraph/popup.cpp
	IntelliGraph/popup.h
	IntelliGraph/popup.ui
	IntelliGraph/popupedge.cpp
	IntelliGraph/popupedge.h
	IntelliGraph/popupedge.ui
	IntelliGraph/workspace.cpp
Next button en AlgorithmInterface

Een arbitraire AlgorithmInterface en bijbehorende next functie
proof of concept SampleAlgorithm

A proof of concept that uses a class SampleAlgorithm that will iterate
over all nodes