help users avoid a common foot gun of specifying labels with references

[kleinschmidt]

A common failure mode of creating custom labels is to specify the labels including references (e.g., just copying and pasting the labels seen in the EDF signal headers), whereas match_edf_label passes the EDF label through _normalize_references which extracts and compares the first part (without reference) with the custom label:

OndaEDF.jl/src/import_edf.jl

Lines 155 to 156 in 735c285

	initial, normalized_label = _normalize_references(label, canonical_names)
	initial == channel_name && return normalized_label

As a concrete example, handling an unusual channel label like 2A-M1 that is known to be left EOG, you might be tempted to use a custom labels spec like

["eog"] => ["left" => ["2a-m1"]]

but this silently fails, sicne the correct specification is

["eog"] => ["left" => ["2a"]]

One way to catch things like this would be to check for whether the channel name is unchanged after passing through _normalize_reference, and raise an error/warning if not. another, trickier approach would be to somehow ALSO handle the "with reference" version so that both "2a" and "2a-m1" would match "2A-M1". but that may introduce subtly breaking changes since we use a greedy approach to matching (return the first thing that matches).