MyCyma

[fix] check artwork properties/subobjects better before displaying

[evol] an artwork can have multiple materials

[fix] renamed 'technique' into more appropriate name 'artwork_support', and update schema and translations (Closes #4)

[cosmetic] center artwork image in their frame in the arwork admin list

[fix] worked around artwork list default sort not enforced

[fix] added 'selected' parameter to artwork size generic selector and pass currently selected size in artwork edit page (closes #1)

[fix] remove hardcoded submit label in display_standard_form_buttons() helper and propagate submit_label view variable to it

Initial version