savana alt/depth from info, added n_alt_depth for info and above for vcf_variant

src/variant/variant_collection.rs

@@ -770,7 +770,7 @@ impl Variant {
         let (n_alts, depths): (Vec<u32>, Vec<u32>) = self
             .vcf_variants
             .iter()
-            .filter_map(|vv| vv.formats.n_alt_depth())
+            .filter_map(|vv| vv.n_alt_depth())
             .unzip();
 
         (mean(&n_alts), mean(&depths))