Path to release 3.4

[maread99]

I'm taking the liberty to assume that the process started with PR #71 (to add a 'side' option and overhaul the test suite) will culminate in cutting 3.4. The process...

• Complete, review and merge side option to define minute bounds / test suite overhaul #71.
• PR to replace ExchangeCalendarTestBase with ExchangeCalendarTestBaseProposal for the first five calendar test modules to which proposed base already incorporated by side option to define minute bounds / test suite overhaul #71 (to include moving over calendar-specific tests).
• Move all calendar test modules over to new test base (over various PRs).
  • Migrate all subclasses of EuronextCalendarTestBase together under same commit
  • When all calendars migrated, remove following classes which are no longer required:
    • OpenDetectionTestCase (minute_index_to_session_labels now comprehensively tested under new suite.)
    • NoDSTExchangeCalendarTestBase (this case is now handled by new test base internally.)
  • End by removing now old ExchangeCalendarTestBase and renaming ExchangeCalendarTestBaseNew as ExchangeCalendarTestBase
  • See if can now lose 'parameterized' from development requirements (change setup.py extras_require and update requirements).
  • Merge Migrate to new test base, 4 #96
• Add new minute-related methods and corresponding tests.
  • PR changes.
• Review whether to move *minute_nanos(side=None) methods , which can currently override default side, to properties that return for default side only (would require revising minute_index_to_session_labels).
  • Change these to properties. Check if minute_index_to_session_labels requires any revisions.
  • PR changes.
• Rename ExchangeCalendar methods (as Renaming of some ExchangeCalendar methods #85).
  • PR changes.
  • Revise/re-run tutorials to accommodate any name changes
  • Revise README to accommodate any name changes.
• Revise README / introduce tutorials (see 'readme' branch, awaiting PR):
  • PR changes
  • Clearly express concepts of 'session(s}' and 'minute(s)'.
  • Explain 'side' option.
  • Update FAQ covering creating / modifying calendars to reference new .md file introduced by DEV: Add a PR template #99.
• Cut 3.4.