[BUG] Harmony pipelines does not give reproducible results

[dweemx]

Describe the bug
The *harmony* pipelines does not give reproducible results in terms of cell embeddings of PCA, t-SNE and UMAP.

To Reproduce
Steps to reproduce the behavior:

1. Configure with these options:

nextflow config vib-singlecell-nf/vsn-pipelines -profile tenx,pcacv,harmony,singularity > nextflow.config
...

2. Run using this entry point:

nextflow -C nextflow.config run vib-singlecell-nf/vsn-pipelines -entry harmony

3. See error:

/ (No explicit errors)

Expected behavior
The cell embeddings of PCA, t-SNE and UMAP should correspond between 2 or more independent runs given the same seed.

Screenshots
Run 1:

Run 2:

Please complete the following information:

• OS: CentOS 7
• Nextflow Version: 19.12.0-edge
• vsn-pipelines Version: v0.18.0

Additional context
Related to #165

[dweemx]

Using params.global.seed = 180, we should get the following results: