Fix inplace variables

[jmitrevs]

Description

Inplace variables are broken in the main branch because they are fixed too early. Subsequent optimizations can make this connection no longer valid. Issue #707 (and the attempted fix in #708) is an example of this issue. This was largely developed in the ingest-qonnx-master branch, but is extracted here, and an omission related to stream repacking for quartus was discovered and fixed.

Type of change

Bug fix

• [x] Bug fix (non-breaking change that fixes an issue)
• [x] New feature (non-breaking change which adds functionality)

Tests

The pytest, test_reshape.py, is the main test, though test_cnn_mnist.py is also pertinent. The new reshape functionality for Intel needs testing, though. There is also the question of whether flatten can always be removed for io_stream. This should be checked further, and if exceptions are found, we may need to change when we run the optimizers.

Checklist

• [x] I have read the guidelines for contributing.
• [x] I have commented my code, particularly in hard-to-understand areas.
• [ ] I have made corresponding changes to the documentation.
• [x] My changes generate no new warnings.
• [x] I have installed and run pre-commit on the files I edited or added.
• [ ] I have added tests that prove my fix is effective or that my feature works. (May want to add another for Flatten. in various cases.)