VERSION 0.90: major ui overhaul — JWildfireSwan Steam update #3726004

I now made a major overhaul of the entire user interface (without changing too much) to offer different styles/themes. With tihs change I introduce a new DARK theme (the new default setting), which contains more subtle elements to differentiate the controls from each other. Also I finally implemented a LIGHT theme. And, the flame-library now shows also thumbnail-previews of the flames. Complete changelog: VERSION 0.90 (29.04.2025): made a major overhaul of the entire user interface (without changing too much) to offer different styles/themes - there is a strange behavior in Godot of transparent textures that get a hue of a parent component. This could not be disabled, but had to be circumvented in several areas of the user interface (usually this is not visible when using only a dark theme/background) - introduced a new DARK theme (the new default setting), which contains more subtle ele...