Empty tests in `master`

[villegar]

The following tests are empty (e.g., contents have been commented out), so perhaps we should remove them and log somewhere else if we are intending to refactor them in a future version:

• test-disc-ds.cor.R:60
• test-disc-ds.cor.R:94
• test-disc-ds.cov.R:65
• test-disc-ds.cov.R:93
• test-disc-ds.levels.R:28
• test-disc-ds.mean.R:23
• test-disc-ds.meanByClass.R:25
• test-disc-ds.var.R:23
• test-expt-ds.reshape.R:18
• test-smk_expt-ds.mean.R:44
• test-smk_expt-ds.mean.R:51
• test-smk_expt-ds.mean.R:58