Composable post-processing steps

[atruskie]

Is your feature request related to a problem? Please describe.

When creating a generic recogniser, the post processing steps are limiting and difficult to work with because:

• they are applied in a fix order
• new filter steps can break existing recognisers
• they apply to all events produced by all profiles

Describe the solution you'd like

A post-processing process that is composable, orderable, opt-in, and can operate on sub-sets of events.

Features:

• The PostPrcocessing entry in the config file should be turned into an map of string-keyed objects
• Each single post processing object should
  • allow for the selection of events from profiles or previous post-processing steps
  • include an array of operations to apply to the selected events
• The current post-processing filters will be turned into individual objects/classes which are deserialized by using a type tag (similar to algorithm selection for profiles)

Describe alternatives you've considered

All these "advanced" cases could be catered for in code in dedicated recognisers - but that means none of this work would benefit any of our users, and would end up being repeated for each recogniser that needed custom code.

Example

PostProcessing:
    default:
      from: "*"
      steps:
        - PostProcessInDecibelGroups
        - CombineVerticalSyllables
    call_one:
      from: [ SyllableUpwardLow, SyllableTailLow, SyllableUpwardHigh, SyllableTailHigh]
      steps:
        - combine_horizontal_events:
        - combine_vertical_events:
            parameters: ...
        - filter_bandwidth:
            bandwidth: "500" #, "500sd100", "500+-100", "[490, 600]"
    harmonic:
      from: "HarmonicParameters"
      steps:
        - remove_enclosed_events: true
        - filter_bandwidth:

        - duration_filter:
    combine:
      from: ["call_one", "harmonic"]
      steps:
        - combine_overlapping_events