models: make 'build_resource_class' more robust
folder: fix Folder_Thumbnail default_icon
Language attr. is required for multilingual fields
Rest: Now it's possible to upload files
Agenda: allday=0 if create new evt. on daily view
Fix jquery bug in js/javascript.js
widgets: fix MultilineWidget if value is not str
config_models: add email to FieldType_Field
Fix thumb quality on PNG / GIF
Emails: add to_addr in **kw in send_email method
Merge branch '0.75'