Annotations: Ellipses

First Step to support Annotations: Ellipses.
Merge branch 'Annotations' into AnnotationsUpdate
Add (first) support for arrows and textboxes
Two test cases:

annotation_01 demonstrates what the new code can do
annotation_02 demonstrates some remaining problems
Remove commented out code
Small cosmetic changes
Move annotation tests into `testfunctions`
Fix indexing bug in ACID test
Merge branch 'annots'

This brings partial annotation support in R2014a and older.
R2014b is not yet supported: the actual objects look the same,
but are no longer stored in an `Axes` but in an `AnnotationPane`

This `AnnotationPane` is stored within the `SerializableChildren`
property (protected) instead of `Children`.  As such, it can only
be accessed through a `findall` (or maybe even `findobj`) call.