Parse url encoded form body to a form struct

[crhntr]

Given a "form" argument is passed to a handler,
And the static method definition has a parameter of kind struct
When I call generate
Then I get a handler function that parses the request body and sets fields

Given a "form" argument is passed to a handler,
And the static method definition does not exist
When I call generate
Then I get a handler function that receives url.Values

Dev notes

In this draft only support one field per name. In the future handle slices with the same name.