update news for upcoming release
Merge pull request #1870 from mazumdarparijat/KMeans_notebook

added real data example in KMeans notebook
Link to doxygen in KMeans notebook for ClusteringAccuracy class
seed the rng to the heisenbug and make the kernel more diagonally
dominant to make it p.d.
Fixed directories in instructions.
Fixed commands regard downloading and preparing shogun-data.
Merge pull request #1867 from tklein23/develop

Added first draft of "quickstart" instructions to documentation.
link quickstart
add empty news boiler plate
added PCA+KMeans in KMeans notebook
minor changes in PCA in KMeans notebook
Merge pull request #1872 from mazumdarparijat/KMeans_notebook

added PCA+KMeans in KMeans notebook
apply_to_feature_matrix method fixed in PCA
PCA unit test added
PCA code changes fixed
fix install of r_static/modular interfaces when DESTDIR is set
add another missing DESTDIR
ssk renamed to SubsequenceStringKernel for naming consistency
Merge pull request #1879 from lambday/develop

ssk renamed to SubsequenceStringKernel for naming consistency
PCA in-place