- where files are required from the "starter" (./src/main/java), these
  are now soft-linked into the example source.
- a couple examples were missing import statements.
- the example code for Hamming was failing the test suite.

At this time, these are all of the problems that have example code.

- enable compilation during CI build only for those that currently pass.
  (let's tackle the failing tests+example code one at a time).

For the related discussion see https://github.com/exercism/xpython/pull/98.