Improvments in Command & CommandArgument classes.

* Updated CommandArgument map creation in Command class.
* Updated CommandArgument value handling in Command class.
* Changed CommandArgument type from String to Class.
* Added new constructor to CommandArgument class.
* Fixed typo in IPublish interface.
Version update from 0.5 to 0.6.0.
Moved core interfaces to separate package

Refactored groundstation object
Introduced IPartOf interface and management