Revert "Avance parcial en refactoring de PkgMgrFrame."

This reverts commit de196e5b441cd8ad04382a11d32c9c21a954fcd8.

Conflicts:
	src/bluej/extensions/BlueJ.java
	src/bluej/pkgmgr/AbstractPkgFrame.java
	src/bluej/pkgmgr/PkgMgrFrame.java
	src/bluej/pkgmgr/Project.java
	src/bluej/pkgmgr/TabbedPkgFrame.java