Added Inverted TrayIcon & Gui Refresh interval metric in GUI

[Tuphal]

I did a fast test. It works after a restart of the program.
Please verify

[dabear]

I'll check it out later this month and create a release

[dabear]

Some of the designer related files have comments in german. That must be converted to english

[Tuphal]

I updated the two files with the auto-generated comments.

[Tuphal]

I encountered the problem, that my selected Background Image was not used after the start.
On every start had to open the settings and click "verify and continue" to use the image.

I made 2 radio buttons to let the user choose a background color or image.
Depending on this setting the load-script chooses the right setting.

[Tuphal]

The change of the background was not a problem of the app, but of my batch file.

Explanation: I have a batch file for all autostart processes.
In these I call start "" "D:\Tools\FloatingGlucose\FloatingGlucose.exe"
The background image is in the same directory, thats why I used in the FloatingGlucose Settings ".\background.jpg" and not the full path.
By calling the app through the batch, the app can not find the background image (I can not explain why). I changed the batch call and then it works:
cd /D D:\Tools\FloatingGlucose\ & start "" FloatingGlucose.exe

Therefore my last change is not needed, but maybe for a more clarified chosen background usefull

[Tuphal]

Added option to start and set window in the background.
Default setting is set to be always on top.

[dabear]

This Pull request is becoming too large in featureset. Please Split out background and alwaysontop in two separate PRs.

[Tuphal]

sorry. I made two separate PRs. How can I undo the changes in this PR?

[dabear]

Gui Refresh interval label can stay. I want the app to always have the same trayicon. I understand that might be an inconvenience. If so, please help me find another royalty free icon that would fit most desktops (win 8, win9, win10++)