Merge branch 'readme-and-logo' into 'master'

convert README.txt to and add a Logo

See merge request !21
8 jobs for lbfgs in 7 minutes and 5 seconds
Name Stage Failure
clang-c++98 Test There is an unknown failure, please try again
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.
CMakeFiles/CoMISo.dir/build.make:302: recipe for target 'CMakeFiles/CoMISo.dir/Solver/' failed
make[2]: *** [CMakeFiles/CoMISo.dir/Solver/] Error 1
CMakeFiles/Makefile2:99: recipe for target 'CMakeFiles/CoMISo.dir/all' failed
make[1]: *** [CMakeFiles/CoMISo.dir/all] Error 2
Makefile:127: recipe for target 'all' failed
make: *** [all] Error 2
ERROR: Job failed: exit status 1