Instead of "@in type name;" we now use "@in name: type;". This change
is done because of consistency with the rest of Eolian; pretty much
every other part of Eolian syntax uses the latter form.
This is a big breaking change in the .eo format, so please update your
.eo files accordingly and compile Elementary together with the EFL.
@feature
You can add in the .eo file the eo_prefix:... and data:... in case
you want to override respectively the Eo prefix and the data type.
If "data: null" is used, no data type will be added.