Xmi

Changelog:
1. XmiManager can now handle Multiple XmiModels. Creation of Entities and Relationships will be done within XmiModel and not XmiManager
2. XmiStructuralSurfaceMember has been implemented minimally to support for geometry exports.

**Full Changelog**: https://github.com/xmi-schema/xmi-schema/compare/0.0.3...0.0.5

**Full Changelog**: https://github.com/xmi-schema/xmi-schema/compare/0.0.2...0.0.3

**Full Changelog**: https://github.com/xmi-schema/xmi-schema/compare/0.0.1...0.0.2

Used to for testing for xmi-schema