Matlab examples fix

First round of changes for the Matlab examples scripts in preparation for the Paris workshop

- refactor `ReadData.m` to make use of the most recent OMERO.matlab functions (getImages, getProjects...)
- use `loadOmero()` to create a connection. assuming `ice.config` is in the path or `ICE_CONFIG` is defined and all the parameters have been defined. This should be further improved to explain how to create a connection without ice.config. This changes allow the script to be tested in a job for now. 
- read `image.id`, `dataset.id` from the `ice.config` file
- add some verbose output to the various read operations

Should be tested by the `OMERO-merge-training-stable` job

/cc @will-moore, @jburel