Bug#978017: opencascade: please, make dependency on libvtk7 optional

[Daniel Serpell]

Source: opencascade
Version: 7.5.0+dfsg1-2
Severity: wishlist

Dear maintainer,

Most applications depending on libocct-* libraries do not need the Vtk visualization
(for example Kicad) and Vtk adds about 220MB of extra disk space.

It would be great if the dependency to Vtk could be made optional (or a recomends), so
that users that does not need the visuzalization can omit it.

Regards,

    Daniel.

-- System Information:
Debian Release: bullseye/sid
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.9.0-5-amd64 (SMP w/8 CPU threads)
Kernel taint flags: TAINT_PROPRIETARY_MODULE, TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8), LANGUAGE=en_US:en
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)