improved error feedback when IDs in queries can not be found

This introduces the or_fail_for_id(id) method to be used instead of
or_fail()? in applicable places

Author: proycon

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "stam"
-version = "0.16.5"
+version = "0.16.6"
 edition = "2021"
 authors = ["Maarten van Gompel <proycon@anaproy.nl>"]
 description = "STAM is a powerful library for dealing with stand-off annotations on text. This is the Rust library."