Update to Zig 0.13

Add docker ignore file
Add auto-update to building of examples

Add support for `RoutingId` and `RouterHandover` socket options

Remove unused ZSocketOptionTag enum
Add `ZSocket - routing id` unit test
See #4
Thanks to https://github.com/7Zifle

Update to Zig 0.12

(examples are still wip)
See #3
Thanks to https://github.com/7Zifle for most of the work!

Fix memory leak on failed `ZSocket.send()`

Change to using libzmq

(instead of czmq)

Add socket options II

Add socket options

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