Modifications of example 1 in section “Simulation” of BornAgain manual in order to match the script given in the Appendix

revised version of BornAgain manual and corrected version of FormFactorBox.cpp (implementation of radius and length)

User manual now can be compiled with cmake in standalone mode (without whole BornAgain), UserManual.tex.in is replaced with shorter version located in cmake/scripts

Writen CMakeLists.txt to build the user manual using CMake. Just switch on the BORNAGAIN_MAN option.

- change font size from 10 to 11pt
- rework title page (main title not less prominent than chapter headings;
  extended subtitle; full affiliation)
- rework introduction (separate paragraph on IsGisaxs)
- reword a few paragraphs