Use PythonPathHelper instead of custom functions to search for Python files in existing folders.
Fix some improper labeling of the Breakpoint Properties menu.

The Breakpoint Properties menu has incomplete-looking titles ("Properties for " and "common"),
so replace them with more appropriate ones.

NOTE: The new contents of the labels are constants, and are thus not reactive to the type of
breakpoint being edited (like Java's Breakpoint Properties menu) because of incompatibilities
between PyBreakpoint and Util.getAdapter.
Update license dates in files of previous patch.
Minor
Merge pull request #57 from AndrewFerr/exsources

Use PythonPathHelper instead of custom functions to search for Python fi...
Merge pull request #67 from AndrewFerr/aferrazz_dev

Fix some improper labeling of the Breakpoint Properties menu.