This reverts commit f448f4f6.

Added changes to .gitignore to readjust which files are uploaded to the repository. From now on, everyone will have to build the tarball locally and install the package locally. The documentation pdf, though, is copied in
the main folder but ignored by the R CMD build.

Re-ordered package structure. Now the pdf is in the main folder, ignored by the R build. The .Rcheck folder and the tarball are now excluded from the project.

First version that passed the thests. Usable but there are details to finish. Eigentechniques not added yet.