minor issues & features: HMI tweaks

Tunnel:

• A good idea could be to use instead of the property "rotated" the "rotate 180°" and/or "horizontal flip"? I think there is not so much benefit from having an mirrored or fully rotated text to encyrpt ;-)
  
• Another idea would be to be able to rightclick on lines to "switch" them to tunnels.
  

variable Resistors, poti, LDR, thermistor:

• the value cannot be changed via the knob, when the simu is off. When changing it via "properties" the knob rotates, but the shown value is not updated.
  

all components:

• is it possible to get a double click event on the components to open the "properties" window? It could be similar to the drag and move event with regard to the area to double click on.
  
• further hotkeys for left / right rotation would be great. for example: Tina TI uses <ctrl>+l and <ctrl>+r on selected components
  
• the marker for selected components differ: e.g. the keypad seems to have a thick line, the voltmeter a thin line, the 7-Seg Display no line / no marker. I do unterstand, that the mcu's are better visible with marking them as inverted - but some other components have it (e.g. switchdip) some other don't.
  

Tunnels:
If you rotate or flip a tunnel the text inside will also rotate/flip.
"Rotated" property is there to avoid that: tunnel is rotated, but text keeps readable.
Thinking about it... maybe the functionality could (should) be implemented into normal flip component function.

Rightclick on lines to "switch" them to tunnels.
Sounds interesting, maybe a little bit complex to implement depending on how it's done.
What should happen for multiple wire connections?

Variable resistors: Ok, will be solved.

Double click to open "properties" window: Sounds like a good idea.

Hotkeys for left / right rotation: Sounds like a good idea.

The marker for selected components differ:
Yes, by default the component box becomes gray, but some components have a widget inside. So the widget is hidding the component box.
Making all components look the same would be possible, but too complex for the benefits.
I think there are other issues that are much more important (by now).
Some of these issues are easy to solve, so it's ok. But some other (like this) require much more time.

like I wrote: most of the requested features are minor - like "polishing a cut diamond"

'Rightclick on lines to "switch" them to tunnels':
The situation of multiple wire connection is a good question. Probably the easiest way in this situation would be to put wire stubs plus tunnels at all connectors of the former multiple wire connection.

A second way would be to implement two options: "tunnel connected wire" and "tunnel pieces of wire". The last one would only "tunnelize" the given pieces.

A third way might to give the user the choice already when he is selecting the wire. Something like:
- single <CTRL>+click on wire (as already given): select single part of the wire
- double <CTRL>+click on wire: select piece of wire from connector to next connector/knot
- triple <CTRL>+click on wire: select all connected wires
(similar to selecting text: https://stackoverflow.com/questions/2575758/conventions-for-the-behavior-of-double-or-triple-click-to-select-text-features)