[IMP] product: search on internal reference

When searching on the name of a product.template, search also on the default_code. Move the filter from product.product to product.template.
The field default_code is on the product.product but accessible through a related field, meaning when reading it will fetch only the first variant but searching on all variants.
Fixes #3399
[IMP] stock: display chained moves

Add field move_dest_id in stock.move form view for better debugging of complexe stock flows.
[IMP][website_mail] improved template designer, added support for background color, font color and bootstrap buttons(inline css) in mail designer,removed other snippet, changed snippet according to new format,added theme selector in mail_designer, lodeded snippets dynamically based on theme, added font-awesome support in mail snippets, added one controller which convert font-awesome to icon

[IMP] Fixed bug of dropzone,improved behavior of edit mode

[IMP] Improved Behavior for selecting theme while designing a fresh template and some other changes