Macro marlu::average_chunk_for_pols_f64

macro_rules! average_chunk_for_pols_f64 {
    (
        // to be averaged
        $jones_chunk:expr,
        $weights_chunk:expr,
        $flags_chunk:expr,
        // to average into
        $avg_jones:expr,
        $avg_weight_view:expr,
        $avg_flag_view:expr
    ) => { ... };
}

compute the weighted geometric average of unflagged visibilities for each time, frequency and pol in the chunks.

If all visibilities in the chunk are flagged, then use the geometric average withough weights.

dimensions:

• jones_chunk -> [at, af][pol] (each element is a complex vis array of length pol)
• weight_chunk -> [at, af, pol]
• flags_chunk -> [at, af, pol]
• avg_jones -> [pol]
• avg_weight_view -> [pol]
• avg_flag_view -> [pol]