Use tabs instead of spaces for indentation.
Clean up code.
On branch master, changes to be committed:
	modified:   src/Lepton.pro
	modified:   src/editortabbar.cpp
	modified:   src/generalconfig.cpp
	modified:   src/leptonlexer.cpp
	modified:   src/mainwindow.cpp
	modified:   src/projectitem.cpp
	modified:   src/projectmodel.cpp