New unmarshalling rules for fields which could be numeric or string
values were not properly typecasted upon being deserialized.
Cleaned up the api template file and moved custom unmarshalling type
logic into go code out of the template.
This commit changes the code generator to generate a `UnmarshalJSON` for each
struct, so that if unmarshalled it properly handles UniFis varying integer values
via the `emptyStringInt` type.
Structs not including a field of `int` type will still have the function generated,
but it will effectively do nothing.
Fixes#18
* Allows for generating top-level types for any embedded struct so
that sub-types can be properly instantiated from calling code
* Specifying `-no-embedded-types` will generate top-level types
rather than embedding the struct
* Refactored "Device" API
* All fields set to `omitempty` because it describes all possible
device types, so effectively any field could be omitted any time
* Fixed `get` call for "Device" API; replacing `rest` with `stat`
* Generated `get` and `update` calls for `Setting*` APIs
* Added `5.14.23` JSON files
