Qore YAML module

Release Notes: This release fixes a problem with deserializing untagged and unquoted integer and floating point 0 and 0.0 values; they were incorrectly deserialized as strings. Additional information is provided when an exception is raised while serializing scalar values (normally this happens when a string has an encoding error).

Release Notes: This initial release provides serialization and deserialization between Qore data structures and YAML strings. All Qore data types (except objects) can be serialized as YAML strings without any data loss, including the microsecond and time zone components of date/time values. Qore durations are handled with a custom YAML type (tag: !duration). YAML string output formatting can be controlled with options to the makeYAML() function. The module requires Qore 0.8.0 as it uses type info and date/time APIs found only in newer versions of Qore.