Redesign the ElemType register

[cv3d]

Merge with opencv/opencv_contrib#1807
replaces #12611
resolves #12584
related #12569

This pullrequest changes

• Increase the supported depth types limit from 8 to 32
  • Introduced uint32, uint64, int64 and other special formats (i.e. raw, auto, undefined)
• Increase the supported channels limit from 512 to 2048 (still extensible with further design work)
  • Use the next available (bigger) number of channels in case of invalid channel input
  • Great impact expected on various modules (e.g. DNN and feature2D)
• Fully-backwards compatible with serialized files generated using older OpenCV versions

force_builders=Custom,Linux32,Win32,Win64 MSVS2017,ARMv7,ARMv8,Android pack
docker_image:Docs=docs-js
docker_image:Custom=ubuntu-cuda:16.04

[cv3d]

Would you mind adding this PR to the 4.0.0-beta milestone?

[cv3d]

@vpisarev I know you are busy, but I wonder what is the current state of this PR. Mind to let me know?

[vpisarev]

@cv3d, it should stay closed until OpenCV 4.0

[cv3d]

We try to do it all by OpenCV 4.0.

As you wish, although I understood previously you desire to do it by now.

[cv3d]

Is there any update regarding this PR, and perhaps the other already closed PRs of mine?

@vpisarev A kind reminder.

[cv3d]

@alalek, @mshabunin, @alexey-sidnev, @dkurt
It seems @vpisarev is not around in the last three weeks, and I wonder if anyone of you can update me on the current situation. E.g. Is there any estimated time on how long shall this PR waits?

I have been waiting patiently for two months, and I no longer feels motivated to contribute due to the way my PRs are being handled, despite my previous contributions for many years by now...
Is not OpenCV an open source project? Would Intel agree on what is happening here?

[dkurt]

@cv3d, you're not alone. I've been waiting for merging my PR into TensorFlow for 4 months: tensorflow/tensorflow#21660. I don't know why Google don't want it 😄

Let's carefully review you changes. I don't think that a single programmer is able to make a decision to merge changes to the core of 20 y.o. library.

BTW, does GitHub allow to reopen your PRs? Why you do not just reopen it?

[cv3d]

@dkurt Thank you for your support. I appreciate in advance all your efforts in review.
It seems as long as a PR is closed by a maintainer, the author cannot reopen it, and only maintainers can.