Annotation should reference Character instead of Allograph

[geoffroy-noel-ddh]

At the moment the annotations are linking to a Script and an Allograph in a definition file.

It would be better to reference the Script and the Character instead.

Why:

1. it makes the annotations more readable and interoperable (Character refers to Unicode; whereas Allograph are defined only in a definition file)
2. it makes the annotations more standalone, indexing & searching can happen without resolution of the character via a definition file
3. it is less redundant: A <-> (S , C)