Feature/130 report cleanup

[nfarabullini]

• Clean up of header.tex and the report
• Inserted a4 format for report
  closes Technical review of R Markdown PDF report #130
  closes A4 PDF report  #131

[riccardoporreca]

@nfarabullini, I think we should not rush things and somehow discuss / plan changes better.

The current status of the branch does not quite address the points in #130, which were in fact just mentioning some preliminary, non-exhaustive examples. Some of the changes even go in the wrong direction.

There should be least some minimal discussion / common understanding about existing issues. Quick implementations with sudden PR, without any sort of discussion or good understanding of what the issue is about is definitely not the way to go.

I am in fact going to close this PR, we should rather go back to the issue first, and re-open a new PR at a later point. We shall also consider reverting the changes on the branch, possibly cherry-picking the A4 format commit e1438f1 in a separate branch dedicated to #131 only (happy to help with and show what this is about, TL;DR: git cherry-pick e1438f16493039132c28bdea094921fc6fed9cb3 )