Code completion in custom views now picks up newly added attrs

When ADT encounters a custom view, it creates a view descriptor for
that custom view, and in ADT 20 it also finds the associated styles
and records these as attributes, which means code completion and the
property sheet will show these properties.

However, once the descriptor has been lazily created, it never
changes.  If you go and edit the styles.xml file specifying the
attributes for your custom view, you need to restart the IDE before
code completion will pick up these changes.

This changeset makes this behavior more dynamic: It will now pick up
edits to the files specifying styles for a custom view.

Change-Id: I365119e18c74378a0a039c1e7a22641c94acf002
4 files changed