Xiana hotreload/livereload

[gmsvalente]

Xiana hotreload/livereload

Description

This PR adds a Hotreload/Livereload to Xiana.

Tester info

Check if server is restarted when saving changes.

Completion Checklist

• Add description of the changes made here to the changelog file
• Update the documentation as necessary

[puchka]

I got this error while testing the hot reloading feature

Exception in thread "async-dispatch-1" java.lang.NullPointerException: Cannot invoke "clojure.lang.IFn.invoke()" because "this.restart_fn" is null
        at xiana.hotreload$hotreload$fn__11268$state_machine__8002__auto____11285$fn__11287$fn__11289.invoke(hotreload.clj:42)
        at xiana.hotreload$hotreload$fn__11268$state_machine__8002__auto____11285$fn__11287.invoke(hotreload.clj:38)
        at xiana.hotreload$hotreload$fn__11268$state_machine__8002__auto____11285.invoke(hotreload.clj:38)
        at clojure.core.async.impl.ioc_macros$run_state_machine.invokeStatic(ioc_macros.clj:978)
        at clojure.core.async.impl.ioc_macros$run_state_machine.invoke(ioc_macros.clj:977)
        at clojure.core.async.impl.ioc_macros$run_state_machine_wrapped.invokeStatic(ioc_macros.clj:982)
        at clojure.core.async.impl.ioc_macros$run_state_machine_wrapped.invoke(ioc_macros.clj:980)
        at xiana.hotreload$hotreload$fn__11268.invoke(hotreload.clj:38)
        at clojure.lang.AFn.run(AFn.java:22)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
        at clojure.core.async.impl.concurrent$counted_thread_factory$reify__1774$fn__1775.invoke(concurrent.clj:29)
        at clojure.lang.AFn.run(AFn.java:22)
        at java.base/java.lang.Thread.run(Thread.java:833)

I made a minimal reproducible example here: https://github.com/puchka/hello-xiana/tree/test/hotreload

[jiriknesl]

Why is this still open? Can we finish it?