Yaks

Fixed
- Bug if eval callback raise exception

Fixed
- In **Eval** string properties can now contain the '='
- Message and Header encoding, support for larger get and put

Changed
- Encoding of properties

Changed
- Evals and listeners are now called in separate threads, to avoid locks on the runtime.
- In **Selectors** changed the separator for the properties from '[' and ']' to '(' and ')' according to RFC3986

Changed
- Internal refactoring of the API
- **Admin** object added to management of YAKS

Changed
- **login** become a static method of YAKS and creates the YAKS API ( YAKS.login() returns a **YAKS** object)
- _put_; _update_; _remove_; _eval_; _workspace_ takes **str** or **Path**
- _get_; _subscribe_ takes **str** or **Selector**
- _get_; _subscribe_ and _eval_; returns **str** as default for _paths_ the optional parameter _paths_as_string=False allow enable returns of YAKS types
- storage creation takes an id and a dictionary of properties with at least the property _is.yaks.storage.selector_ set with a valid **str** or **Selector**

Added
- **Value** class for values
- **Path** class for paths
- **Selector** class for selectors
- _eval_ takes a function that accept a **Path** and other parameters (they are passed as kwargs, all values are string) and return a **Value**
- CHANGELOG.md
Changed
- **login** has to be used for accessing YAKS
- **Access** is renamed as **Workspace**
- **delta_put** is renamed as **update**
- **close** is renamed as **logout**

- _put_; _update_; _remove_; _eval_; _workspace_ takes **Path**
- _get_; _subscribe_ takes **Selector**
- storage creation takes an id and a dictionary of properties with at least the property _is.yaks.storage.selector_ set with a valid **Selector**

Removed
- **Storage** class