Move to `untwine` from `entwine`

Because:
- `opendronemap/odm` is now bundled with `untwine` not `entwine`

Update the symlink creation in the `Dockerfile` to symlink `untwine`
instead of `entwine`. This allows the creation of 3D models for WebODM.

Links
- Change in `opendronemap/odm`: [Entwine ->
  Untwine](a2040b2274)

Dockerfile

@@ -7,7 +7,7 @@ USER root
 RUN apt-get update && apt-get install -y curl gpg-agent
 RUN curl --silent --location https://deb.nodesource.com/setup_10.x | bash -
 RUN apt-get install -y nodejs unzip p7zip-full && npm install -g nodemon && \
-    ln -s /code/SuperBuild/install/bin/entwine /usr/bin/entwine && \
+    ln -s /code/SuperBuild/install/bin/untwine /usr/bin/untwine && \
     ln -s /code/SuperBuild/install/bin/pdal /usr/bin/pdal