Added some tests for PComboBox and added getters for canvas and pSwing

Issue 69 ; adding POffscreenCanvas to extras, with unit test and example

minor style fixes

Issue 79 : removing testReferences method which incorrectly depends on certian behaviour from the garbage collector

Issue 59 ; updating license date range to include 2009

Fix for Issue 9: PComboBox does not work when nested in a Panel ...

Modified TestPSwing to demonstrate the defect and patched PComboBox with the fix.

Added missing copyright.

Fix for issue 8: PSwing nodes prevent proper garbage collection ...

Added a test case that adds a PSwing node, removes it, and checks for remaining references.  Prior to this fix the memory was not reclaimed even after removal.

issue#49 issue#48 done for the first. Is it still compatible?

issue#49 issue#48 - much more elegant plus delegates but also less robust (sic\!). Maybe we'll keep the previous version...

issue#49 issue#48 - comments and minor improvements.

issue#49 issue#48 - pull out an extension point.

issue#49 issue#48 - possible solution.

Issue 59 ; copyright start year should be 1998 to match oldest files

Issue 59 ; updating license header and adding one where missing

Issue 29 ; Tweaked checkstyle configuration and ran eclipse formatter on the java source in extras. Reduced checkstyle errors from 15693 to 3520. Note this commit contains formatting-related changes only, no code changes.

issue#48 started a unit test

issue#51 aligned package and class names of the tests with the classes under test.

Fix for issue 46: PFrameTest unit test fails on linux

issue#44 subdirectory and artifact rename