String handling improvment

[1technophile]

Following this discussion improve string handling on the projects https://github.com/1technophile/OpenMQTTGateway/pull/154

And multiply trc functions with different signature to avoid use of string into trc argument

[broekema]

Thinking about this, we could probably generalize the publishing of messages into a global function or method used by all other code. In this function we can then differentiate between Uno and ESP targets, but only once and at a well defined central location.

[1technophile]

Great idea !

[posicat]

This is where a JSON library could come in handy, might want to evaluate that and this topic together as one change.

[1technophile]

Good point @posicat, we might first try to include json publishing before or in the same time of that

[broekema]

I've create pull request #168 for discussion. This is a class based sensor refactor, that centralizes publishing of messages.

[1technophile]

Implemented arduinolog for traces, and centralized pub functions