DMN15 — Typos in meta model

There are several typos in the meta model that implementers using the XMI files have to patch in their tools in order to match the XML schemas:

1. In the DMNDI13.xmi:

      <packagedElement xmi:type="uml:Class" xmi:id="_18_1_f7a0369_1441612964861_428140_5975"
                       name="DC::Style"
                       isAbstract="true"/>

The class cannot refer to dc:Style as such class does not exist. The XSD refers to di:Style. (see also: https://github.com/omg-dmn-taskforce/omg-dmn-spec/pull/8/files)

2. In DMN14.xmi:

            <ownedAttribute xmi:type="uml:Property" xmi:id="_17_0_3_1_42401a5_1375643571589_681805_3414"
                            name="input&#xA;"

Attribute name includes an encoded newline character (`\n`) which is not present in the XSD. (see also: https://github.com/omg-dmn-taskforce/omg-dmn-spec/pull/7/files)

3. In DMN14.xmi the default value contains encoded special characters:

               <defaultValue xmi:type="uml:LiteralString"
                             xmi:id="_17_0_2_3_ea50349_1446150762540_477393_4060"
                             value="&#34;text/plain&#34;"/>

(see also: https://github.com/omg-dmn-taskforce/omg-dmn-spec/pull/7/files)

4. There is a typo in the contextEntry property of dmn:Context:

<packagedElement xmi:type="uml:Class" name="Context" ...>
  ...
  <ownedAttribute xmi:type="uml:Property" name="contextEnrty"...>
    ...
  </ownedAttribute>
</packagedElement>

See https://github.com/omg-dmn-taskforce/omg-dmn-spec/tree/v1.3/xmi/DMN13.xmi#L1533
(see also: https://github.com/omg-dmn-taskforce/omg-dmn-spec/issues/12)

5. Waypoints property has different names in XMI (wayPoints) and XSD (waypoint)
(see also: https://github.com/omg-dmn-taskforce/omg-dmn-spec/issues/11)

6. Missing property "id" in the DC::Style aka DI::Style
(see also: https://github.com/omg-dmn-taskforce/omg-dmn-spec/issues/10)

7. Wrong packageURI for DMNDI in DMN semantic meta model

Fix meta model typos

Fix several typos in meta model (XMI) that are not consistent with the XML schema (XSD).