Introducing UI update lock.

[RobinTail]

Closes #184

[coveralls]

coverage: 100.0%. remained the same when pulling 4629855 on ui-update-lock into 996f9ce on develop.

[RobinTail]

i don't like this approach, since the next call of this method can be caused by the most recent data state, while the payload for ongoing execution may already have been shaped. that can lead to missing the important updates. what is really required is an actual thread lock that awaits to be released.

yes, but this way it does not solve the original issue

[RobinTail]

Hey, girls, I have an idea — we should not call the UI update fn in the polling thread during the ongoing one caused by the main thread.
The simple bool should be enough.

[RobinTail]

Looks better.
It's always nice to talk to a smart person, thanks for stepping in.

[RobinTail]

Now we can call the UI update fn wherever it's needed, without relying on the polling thread.
For instance — after calling the relay toggling fn.

[RobinTail]

ok