Refactor Java/Matlab list conversion unit tests

- Improve the exposition of the tested input/casting types
- Add {u}int{32,64} to the supported types in toMatlabList()
- Compare elements using == instead of assertEqual and handle the elements class test separately
Add support for string/java.lang.String conversion

- Allow to pass cell array of strings to toJavaList()
- Allow toMatlabList() to read a java.util.ArrayList of java.lang.String
- Implement corresponding unit tests
Improve headers of Java/Matlab list conversion functions
Support string conversion into java.util.Array (as java.lang.String)
Add function to list OMERO annotation types

- Create generic function to generate OMERO class dictionary
Add function to get annotations of specified type linked to specified object
Create shortcut functions to retrieve annotations linked to images
Add a function to download the file content from a file annotation
Rename getAnnotations() as getObjectAnnotations()
Add support for XML annotations

- Add xml to the dictionary of annotation types
- Add function to retrieve XML annotations linked to images