Bump version to 0.22.0.

VariantValue: use WriteArray method for writing arrays of Variant. (#329

)

Make static Signature signature properties internal. (#324)

VariantValue: eliminate breaking changes for values that hold ObjectP…

…ath or arrays of ObjectPaths. (#323)

Protocol: support tunneling the connection over a Stream. (#301)

Bump version to 0.19.0. (#294)

Bump version to 0.18.0 (#284)

Fix DisposeTriggersRequestAborted test.

Bump version to 0.16.0. (#230)

Bump version to 0.15.0.