Added default= parameter to xml_subelement_{attr,text} which specifies what value to return in case the requested node/attribute is not found
Fixed edge case when year was None and compared (>) to int; defaulting value to 0
Added quiet= to xml_subelement_* methods to prevent raising exceptions in case conversion fails
Added quiet=True for function calls where conversions are involved,to prevent raising exceptions in case of malformed data
Updated changelog and version
Merge branch 'release/0.6.0'
Merge tag 'version/0.6.0' into develop

0.6.0