Xpra: Ticket #2563: trim bundled icons

We reduced the size of the win32 builds in #2550 but thanks to r25081 (for CSD and windows with a header bar), we've gained more than we had lost!

Find a way to trim the icons we bundle, and more importantly the metadata that goes with it.

Tue, 04 Feb 2020 09:39:02 GMT - totaamwin32: status changed; resolution set

Done in r25141.

We've shaved off over 10MB of icon data we don't need and more importantly countless files which slowed down the installer.

Thu, 06 Feb 2020 09:01:04 GMT - Antoine Martin:

(this also fixed the missing theme icon: #2531)

Sat, 23 Jan 2021 05:54:42 GMT - migration script:

this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/2563