Transparent zoom minus and plus (v5)

[mrflix]

While I understand the usability concerns, my client insists that the plus and minus symbol inside of the magnifier glass should be transparent. Setting --pswp-icon-color-secondary: transparent makes the plus and minus disappear:

What I'd expect to happen is that the plus and minus mask the magnifier glass:

This would also enable setting the secondary color to half-transparent color that lets some of the background shine through.

[dimsemenov]

Thank you for the pull request, but it's way too much SVG code to add, it's almost the same as all existing icons combined. The existing icons are intentionally very simplistic and optimized for size.

So unless there is a way to make such icon much smaller, I'm not sure if it's a good idea.

Feel free to use the option zoomSVG to override the default icon, or use CSS.

[acwolff]

To taggle that problem, I make in my own css code –pswp-icon-color-secondary white except if --pswp-icon-color is white, in which case I make --pswp-icon-color-secondary black.

I think the icon is a little too small compared to the other icons.