added methods for changign the OBDD and positions of nodes
modified some default values
added optional OBDD names and naming methods, mainly for the Apply method
changed the toQOBDD and toROBDD methods to just reducing
some minor fixes
added a class to represent the visual OBDD as a JComponent
adapted the OBDD controller to the new VisualObdd class
some minor changes
moved the OBDD showing method from the ObddController class to the MainGui class
changed some properties of the AbstractObddLayout and the VisualObdd classes so that an OBDD is now shown, but way too small
added a method to find a specific node in an OBDD
changed a few button labels
added a controller class for VariableOrderings
minor changes