v1.6.0 - Lax Element / Composite Validation

Change summary:

[4862d4e] Throw EDIStreamException if end of input reached before grammar complete (runtime)
[028145c] Allow transaction schema to be set through the header's END_SEGMENT (API)
[56d30af] Add option to declare xmlns attributes on TRANSACTION element (API, EDIInputFactory option)
[#23, #24] Support for lax validation of simple elements and composite elements