add lazy version of track dataset and detection parser

Detection parser can accept a stream of file contents to lazily load files only when they are needed

… made to TrackDataset in subclass

…ode duplication with python track parser

make some functionality reusable through classmethod
use bzip 2 json stream reader to sort files by start date

renamed BulkPythonDetectionParser back to PythonDetectionParser
extracted methods for creating PythonDetections and PythonTracks as static methods on module level

i have some old ottrk files for testing that could no longer be parsed
a new metadata format fixer fixes the old date string format by transforming it to timestamp format
TODO: review versions of fixer

clean up streaming parser and add more doc strings

found potential memory leak: delete det_list in StreamOttrkParser.parser()
OttrkVideoParser crashed in a manual test because the metadata format did not match -> apply format fixer

…n_application.py

also reduced code duplication in cli.py and main_application.py

also fixed/adapted tests

…b.com/OpenTrafficCam/OTAnalytics into OP#3648-create-streaming-track-parser

fixed test_cli patches

…in SingletonTrackDataset

now a chunk size can be specified, tracks will be loaded from the track files until n tracks are collected
the collected tracks are transformed into a TrackDataset, the caller of StreamingOttrkParser can specify a TrackDataset factory

…o be stateful to allow for incremental result exports

Added ExportMode to various export specification data classes:
ExportMode Overwrite for non incremental result export
ExportModes INITIAL_MERGE, MERGE to append data
ExportMode FLUSH to write out results aggregated in stateful exporters
All exporters now consider this export mode

Introduced missing EventExportSpecification to be more similar to other exporters

If first event export has no events the resulting csv/excel have no header, as the data frame is empty, therefore specified all columns as header list

Fixed bug in EventRepository:
clear previously only checked for the existence of (section)events, if none existed nothing was cleared, even if non_section_events were present

stateful exporters for counts require to be cached in a newly added CachedExporterFactory

Added merge_into_dict functions to TracksMetadata and VideosMetadata to allow for incrementally updating a dict with metadata updates

fixed bugs:
no longer use Counter in CsvExport of COunts, instead manually increment counted tags using defaultdict

Streaming parser now has a set of VideosMetadata and TracksMetadata. instead of a list, to avoid duplications

write event list data frame even if empty

OTAnalyticsStreamCli and OTAnalyticsBulkCli both use same attribute name _track_parser

Added error messages to assertions when comparing file content

fixed type annotations for write mode

…comments

removed unused class SingletonTrackDataset