PartialCalParser doesn't need StructTransformer anymore

StructTransformer works fine in a context of cal file parsing, but
it failed when we try to parse some alone string expressions
Implements network variables declarations
Implements instance parameters management
Refactoring

Instance Parameters become Instance Arguments. This is coherent with
call procedure (which defines parameters) and the call of this procedure
(which uses arguments)
When saving data in model, pass the origin widget to the method
Implements generic load/write feature for basic properties pages
Implements loading/writing values from/to models
Allow user to use RETURN key to save values