Implement capability HTTP and downloads (#54)

crates/libremetaverse-structured-data/src/notation.rs

@@ -802,7 +802,7 @@ fn sorted_entries(values: &HashMap<String, OSD>) -> Vec<(&String, &OSD)> {
 }
 
 fn decode_base16(value: &str) -> Result<Vec<u8>, &'static str> {
-    if value.len() % 2 != 0 {
+    if !value.len().is_multiple_of(2) {
         return Err("invalid notation LLSD base16 length");
     }
     value