Split a fixation report into a list of hierarchical dataframes

Usage

split_fixation_report(
  report,
  drop_empty_columns = TRUE,
  drop_saccades = TRUE,
  drop_prev_and_next = TRUE
)

report: Fixation report dataframe as created by read_fixation_report.
drop_empty_columns: Logical. If TRUE, columns that are all NA will be dropped.
drop_saccades, drop_prev_and_next: Logical. If TRUE, columns related to saccades and previous/next fixations/saccades will be dropped.