While the test suite passes, this commit yields a broken server: replacing ad hoc request objectss with PSR-7 ones is still required, as is emission of PSR-7 responses. Both will come in subsequent commits, with tests
Diactoros was chosen specifically because it includes facilities for emitting responses, something which is awkward to test. The end of this refactoring should see both the Response and Request classes disappear, and the general REST class fully covered (as well as any speculative additions to AbstractHanlder).
- Changed 'transform' method to use ValueInfo throughout. This fixes a number of obscure bugs
- Changed the 'add' and 'sub' methods to default to "now" rather than null. This means null passes through rather than being interpreted as the current time, to be consistent with other date tools
- Also changed the 'add' and 'sub' methods so that they operate correctly with invalid date strings
- Added tests for the class; improves #66
- Modified TTRSS tests because the "iso8601" format string in ValueInfo is different from Date's older format
Also move date formats to the ValueInfo class
Standardizing on immutables avoids any possible ambiguity in the API of the resultant value, as well as any ambiguity as to whether a DateTime output instance is the same instance or a clone (they had been clones)
