Merge pull request #14 from NikolausDemmel/master

Minor non-code fixes
Update CMakeLists.txt

make it compile on ARM
Merge pull request #15 from kalectro/master

cmake changes for ARM
restore diagonal in Levenberg

Backup and restore the diagonal in Levenberg.
This should solve some numerical issues, if lambda (the value added to
the diagonal) is huge. Substracting it may "recover" the wrong values.
MSVC Patch by Jonas Witt