📣 borb release notes

This release refactors the testing in borb.

• All tests have been refactored into directories corresponding the main functionality they test
  • E.g. tests for Equation (in borb.pdf.canvas.layout.equation) can be found in tests.pdf.canvas.layout.equation
  • Tests derive from TestCase
    • TestCase offers some utility methods to standardize output files
    • TestCase offers the methods to visually compare an output
    • TestCase offers the methods to check a PDF using a validator