Image file upload required

[martindholmes]

We now have a real use-case for annotation of images using BreezeMap. That works fine when the image is pre-configured in the page, but the original plan for this scenario was to allow anyone to upload any image, and that isn't currently supported. It's time to get this working.

[martindholmes]

Working on this in branch issue-57-upload.

[martindholmes]

The basic plan is this:

1. Create a new startup parameter allowImageUpload which, if combined with allowDrawing, would cause an additional item to appear on the Draw menu, "Upload image".
2. Implement the uploadImage functionality, which would require (presumably) acquiring a Blob, parsing it to get its dimensions, then displaying it appropriately.

[martindholmes]

Basic upload is working; now we need to figure out what other things should be yoked to it. First thoughts:

1. Clear all existing features, but not taxonomies and categories; this enables one project to configure a setup with taxonomies and categories that work for it, and retain them between changing images.
2. Allow drawn features to be assigned to existing categories somehow, perhaps when assigning a caption to the feature.
3. For now, suppress the File upload feature in the demo project, since we don't really have a working implementation of that yet anyway.
4. Set opacity to 1 in by default for an image markup scenario.
5. Allow deletion of a drawn shape in the interface.
6. Consider how we might use tei:zone instead of/as well as location.