Removed unused icons

GUI/coregui/Views/widgetbox/images/sample_edithlayout.png

GUI/coregui/Views/widgetbox/images/sample_editvlayout.png

GUI/coregui/Views/widgetbox/images/sample_spacer.png

GUI/coregui/Views/widgetbox/images/sample_vspacer.png

GUI/coregui/Views/widgetbox/widgetbox.qrc

GUI/coregui/coregui.qrc

GUI/coregui/images/append.png

GUI/coregui/images/bringToFront.png

GUI/coregui/images/clear.png

GUI/coregui/images/config.png

GUI/coregui/images/ellipse.png

GUI/coregui/images/exclude.png

GUI/coregui/images/fileopen.png

GUI/coregui/images/filesave.png

GUI/coregui/images/include.png

GUI/coregui/images/jTxpL5ELc.png

GUI/coregui/images/mode_exp.png

GUI/coregui/images/mode_fit.png

GUI/coregui/images/mode_job.png

GUI/coregui/images/mode_sample.png