feature: add tcp server option

[janwilleke]

If activated, a tcp server opens on the selected port, waiting for connection to forward ble serial device. Strictmode can be reworked or ignored because, if connected no other tasks are todo.

[kai-morich]

Thanks for your contribution. This could be useful for all my Terminal apps but on the other side I want to keep them as simple as possible to provide them as foundation for all interested developers. I could think of a github wiki, linked from all 3 terminal repos, where enhancements in forked repos (like yours) could be mentioned.

[zenbooster]

Something like this: https://github.com/zenbooster/SimpleBluetoothLeTerminal =) janwilleke, I didn't notice that someone had already done this... Can it work in the background?