Use SVG icon for splashscreen

[vlsi]

This change makes the image look better in macOS 2x resolution (e.g. compare the screenshots with #563 ).

I'm not sure we need .png logo in case we use .svg.

IntelliJ:

Darcula:

SolarizedLight:

SolarizedDark:

System (macOS):

Motif:

Nimbus:

Metal:

Fallback (in case svg resource is not found):

[vlsi]

Just in case:

• Label.disabledForeground. It is missing in Nimbus (darklaf converts it to red), and it is white in Motif

• textInactiveText: missing in Nimbus.

• ComboBox.disabledForeground: missing in Nimbus. It has a strange color in Metal.

• Button.disabledText: missing in Motif

So far it looks like there's no color name that could be used universally for "disabled label foreground".

@weisJ, what do you think if a fallback was added to IconColorMapper so it could try multiple colors?
Something like "try Label.disabledForeground, if missing try textInactiveText, if missing try Button.disabledText if missing try Label.foreground, otherwise use #ff0000"?

[weisJ]

I have added the option to add fallback keys. They are declared in the LinearGradient with fallbackKeys="key1,key2,key3,...". You can try it out with the current master branch of darklaf. The id is still the prioritised key.

[vlsi]

So the syntax is either

    <linearGradient id="Label.disabledForeground"
                    fallback="textInactiveText Button.disabledText">

or

    <linearGradient id="Label.disabledForeground"
                    style="fallback:textInactiveText Button.disabledText">

[weisJ]

It would be:

<linearGradient id="Label.disabledForeground"
                fallbackKeys="textInactiveText,Button.disabledText">
   <stop offset="0" stop-color="#4d4d4d"/>
   <stop offset="1" stop-color="#4d4d4d"/>
</linearGradient>

[vlsi]

Just in case: I've actually tried, and fallbackKeys="textInactiveText,Button.disabledText" does not really work.

There's no keys in weisJ/darklaf@e117205#diff-20761adcf666eb958134331292e43dacR96

[weisJ]

Yeah I changed it and forgot about it.

[vlsi]

There's about window:

I guess should be updated as well

[vlsi]

IntelliJ

Darcula:

[vlsi]

So far it looks good to me, will commit if there are no objections.