Enable faster file-finding when debugging linked files.

When debugging linked files, Eclipse now searches for a the file in the current project that
matches the link target rather than asking the user to choose the correct file out of a list
of applicable ones (which happens if multiple files link to the same target).
When searching a project for a file to open, search through all referenced projects as well.

In PySourceLocator, searching for a file to open with createEditorInput now not only searches
the project passed to it for the desired file, but all of the referenced projects too.
Console hyperlinks that link to errors now link to files in the launched project.

Rather than opening an arbitrary appplicable file, hyperlinks that appear in the console
when an error occurs now attempt to open a file in the most-recently launched project
when clicked.