Normalizations, Feature Selections, DimReduction S3 class, (Iterative) Lsi Implementation, Partial function framework, Clustering changes and Framework

[immanuelazn]

Meta-PR that describes the culmination of efforts of multiple features.

Included and previously described features:

• Iterative LSI design docs ([r] add iterative lsi design docs #167)
• Log, tf-idf normalization functions ([r] add tf-idf and log normalization functions #168)
• Feature selection by variance, dispersion, mean accessibility ([r] Add feature selection methods by variance, dispersion, and mean accessibility #169)
• LSI, var feature selection ([r] add lsi, var feature selection #156)
• Rewrite of LSI to utilize normalizations ([r] Rewrite LSI/binned feature selection to utilize new normalization functions, add DimReduction S3 Class #181)
• Current efforts of iterative LSI

[immanuelazn]

Not too happy explicitly describing usage of partial functions here. Perhaps we can replace this once the test data is in, and we can show the small vignette with norms, feature selection, clustering + LSI. On top of that, we can just show usage directly with examples.