Implement predefined default template

[pedrogit]

Add a new view "predef_template" property. For now, possible values are:

• custom
• horizontal_label_popup_edit
• horizontal_label_inline_edit
• vertical_label_popup_edit
• vertical_label_inline_edit
• nolabel_inline_view_and_edit
• grid

When custom is selected the template is taken from item_template (which should be renamed "custom_template")

It would probably be better to have a "Easy template/Custom template" boolean button. When enabled the user then can config the easy template with some options like:

• Horizontal, vertical, or no labels
• Inline or popup edit
• Aligned, stacked or grid controls

When Custom template is selected, the template is defined by a custom string