Version 0.10.1

This version includes:

• Clear documentation what the minimum supported version is, currently rustc 1.51
• A new optional feature old_rust that drops minimum required version down to rustc 1.36 see #33 and the documentation for details. Thanks @mitsuhiko for the idea and @steffahn for the help.
• A new example examples/owner_with_lifetime that showcases a self-referential struct with lifetime in the owner.