scrubbbbs

The general image loader has the content type for wrong extensions so this could be remedied.

Fixes https://github.com/nomacs/nomacs/issues/464

@leejuyuu Thank you for reviewing. I have been testing by setting QT_SCALE_FACTOR environment variable, which AFAIK is effectively what you get on a HiDPI display. In actuality my display is...

@leejuyuu yes, that is correct. My feeling is that this is expected behavior, though I haven't researched other viewers in this regard. Also, it should make anti-aliasing look better as...

After further research I have determined this is not the correct solution, so I'm closing it. QT_FONT_DPI=xx is the correct environment variable to change the UI scale which has all...

Closing due to old issue. There is no "exit" option when rotating images.

New default dark theme (based on new light theme)  With dark purple background  With dark red background. Maybe useful for astronomy. 

> At [02b2b28](https://github.com/nomacs/nomacs/commit/02b2b287a6647e2b7273080fc1950907c830aae4) #617 persists, on Arch with Sway WM, Qt 5.15 This is really bizarre. My first thought is you tested it without `make install` which is needed to...

> not reproduce the glitch of #885, so not sure whether it is fixed or not Nice catch. I checked it again and you are right, it is not fixed....

> For #699, I feel that the blue font color is the cause that's unconfortable to read. Does the color encode meanings like log levels? Do you think it might...