TODO: Fully test and document iter_errors

[VisLab]

This generator has been added (by request) PR #1052 and preliminary testing passes, but needs more extensive testing before release.

The iter_errors is a generator that converts HED issues (which are nested dictionaries into flat dictionaries that include the context). The standard context keys are:

    CUSTOM_TITLE = 'ec_title'
    FILE_NAME = 'ec_filename'
    SIDECAR_COLUMN_NAME = 'ec_sidecarColumnName'
    SIDECAR_KEY_NAME = 'ec_sidecarKeyName'
    ROW = 'ec_row'
    COLUMN = 'ec_column'
    LINE = "ec_line"
    HED_STRING = 'ec_HedString'
    SCHEMA_SECTION = 'ec_section'
    SCHEMA_TAG = 'ec_schema_tag'
    SCHEMA_ATTRIBUTE = 'ec_attribute'

The standard error keys are:

• 'code' -- the standard HED error code
• 'message' -- the error message
• 'severity' -- 1 is error and 10 is warning.
• 'url' -- the web page in the HED Specification corresponding to the error (has explanation of how can occur).
• 'source_tag' -- the source tag that caused the error if application.

Note: #candleindark con/validation#1 It is available in hed/errors/error_reporter.py