Improved test code of SearchPresentationCompilerTest

This makes it easier to produce new tests and makes
them more robust (i.e. we don't have to pass the
location manually)

Fixes #1001687
Merge pull request #30 from mads379/1001687-improve-test-code

Improved test code of SearchPresentationCompilerTest
Provides API for finding potential occurrences

This includes a new component, ProjectFinder, which is
responsible for finding the transitive closure of project
dependencies in the Eclipse workspace.

Additionally I added a new method to Index that allows the
API user to search for a given word in the index of a set
of projects.

Tests are included.

Fixes #1001663