[IMP] website snippet new option, gallery

website.snippet: The methods described in javascript will be called automatically from the data-method_name = value on li snippets options. The methods are called in the order relative to children of xml (eg: <li data-method1=value1> ... <li data-method2=value2> ... </ li>, the method1 is then called method2). Methods receive two arguments: type (over, click, reset) and value. data-snippet-id-option becomes data-snippet-id. Several xml options can use the same data-snippet-id.

add a new gallery snippet

convert website_sale to the new option system
[IMP] Use radio widget in various views

+ some UI messages improvements

(Closes #1913)
[IMP] website.theme: add button in customize theme modal to show all theme modules
[ADD] Creation of a module to send documents via classical postal ways. This module uses the DocsAway web service. It allows to send single documents or multiple ones (thanks to selection in list views). Here, invoices and sale orders are ready to use