This needs PolyMathOrg/DataFrame#237 to be merged.

* master:
  refactor: Rename Variable where we make the roles of the objects clearer in the tests.
  test: clarified the name of a test.
  fix: corrected a comment.
  test: clarified naming using domain language (repeated roots).
  fix: corrected the comment.
  test: added some interesting and missing tests.
  test: changed the example and added a comment to make it clear what the coefficients correspond to.
  test: added a simple test for x^2 + 2x + 1, whose roots are x = -1 and -1
  refactor: Rename Variable - it looks like it is a root.
  stylg: removed redundant comment.
  refactor: Rename Method, and now we have the interface that a client (in this case the test) needs.
  refactor: Inline Method as it has no clients.
  style: corrected a Smalltalk code critique.
  refactor: clarified the name of the method.
  refactor: Inline Method, as it has no clients.
  refactor: Move Method to a more sensible place.
  refactor: made the method a class method. Next we can inline the instance method.
  refactor: Extract Method where a method instantiates a root finding algorithm with the desired precision.
  refactor: migrated the client to no longer use roots message.
  refactor: using Parallel Change, introduced a new message that returns roots in order.

Update baseline dependencies.
Also reduce baseline long method.
Update Roassal deprecated class names.

…ween different Pharo versions