first draft of LT description
Added logic tree structure description
First part of the risk component of the manual
updated logic tree section
Updated description of GMPEs
improved output description
added .ps plots and updated gitignore accordingly
Revised and updated chap 1
Merge branch 'haz-marco' of github.com:GEMScienceTools/oq-engine-docs into haz-marco
Revised and improved Chap 2
Merge branch 'haz-marco' of github.com:GEMScienceTools/oq-engine-docs into haz-marco
revised and updated chapter 3
Changes to chap 4, glossary and gmpes description
Added in the appendix the list of MSRs
completed chapter about demos
merged remote branch and solved merge conflict
completed section about GMPEs
small correction about absolute uncertainties
added figures for demos folder
review of Vitor's branch