Refactoring of modules

[exellian]

currently the naming of files in modules is not consistent. In the end every module which is an directory should use for example the following format:

e.g surface:

• mod.rs - containing the surface definition
• attributes.rs - containing Attributes
• builder.rs - containing Builder
• event.rs - containing Event
• id.rs - containing Id

the current structure is:

• mod.rs - containing only use statements
• surface_attributes.rs - containing SurfaceAttributes
• surface_builder.rs - containing SurfaceBuilder
• surface_event.rs - containing SurfaceEvent
• surface_id.rs - containing SurfaceId