separate project for Isabelle/Pure and PIDE classes using Swing or other Swing-based UI libraries;
this will allow to keep Isabelle/PIDE and Pure UI-independent to some extent
copy files depending on swing/awt/javafx/jfree to pure.ui

Updated dependencies: GraphView and jEdit depend on pure.ui
isabelle.pure and isabelle.pide no longer have UI dependencies

The Swing, AWT, JavaFX and JFreeChart dependencies moved to isabelle.pure.ui.
new library dependency introduced in isabelle.pure
explicit dependency on PIDE for each project
Merge branch 'pure-ui-split'