This function modifies the init file of a package by setting the default value of key.
The package Chordal does not have any configuration options, but its dependencies Graphs and MapleInterface do. For instance, the command
setDefaultConfiguration("Graphs","DotBinary","circo")
sets the Graphviz binary used for visualizing graphs and chordal networks.
This method assumes that the package was installed in the applicationDirectory.
The object setDefaultConfiguration is a method function.