bug#28644: Missing icons in pulseview

[phodina]

Hi,

recently I used Pulseview to debug eMMC issues.

I was also surprised why they are some icons and others are missing.

Based on the code some are implemented as png and some as svg.

I tried to add the qtsvg-5 but it did not work and made the resulting derivation larger.

Therefore there are 2 possibilites: 

1. Add support for SVG by adding qtsvg-5 and any additional packages [1]
   This would be preferable as the images are displayed in the time series and the bitmaps will look ugly.

2. Convert all into pngs
    This will save size but will require a big patch (which will be mostly binary)

What do you think? 

[1] https://sigrok.org/bugzilla/show_bug.cgi?id=239

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Petr