Add support for EventsTable

[oruebel]

Overview

In NeurodataWithoutBorders/nwb-schema#645 the following key changes are made:

1. added new types EventsTable, TimestampVectorData, DurationVectorData
2. deprecated AnnotationSeries

Approach

• Update schema in AqNWB to support the latest core NWB schema. See http://nwb.org/aqnwb/nwb_schema_page.html for instructions.
• Add new classes for representing EventsTable, TimestampVectorData, DurationVectorData. See http://nwb.org/aqnwb/registered_type_page.html for instructions.
• Add methods to EventsTable to simplify recording of events since this will require update to multiple columns in a table
• Update NWBFile to add the required macros (e.g., DEFINE_UNNAMED_REGISTERED_FIELD) for reading and creating EventsTable objects
• Optional: Add convenience methods in NWBFile to simplify creation of EventsTable for acquisition
• Update the user-docs to add a tutorial on using EventsTable for recording events`, incl., adding an example in tests/examples
• Add comprehensive unit tests for the new features
• Update the CHANGELOG