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
FindQGLViewer.cmake update
Use unique name for the header include guard macro.
mingw cross-compile patch by Pablo D'Angelo
update README to highlight the license of CHOLMOD

CHOLMOD is partially licensed under the GPL. As some parts of g2o are
linking to CHOLMOD, this might affect the license of the binaries. If
you want to avoid the GPL, either use other solvers in your binary
(e.g., CSparse, Eigen) or be sure that your CHOLMOD library does not
include the features licensed under GPL.
add clearParameters()
SE2 -> Eigen::Isometry2d() cast operator
Adding tictoc profiling utility code
Merge branch 'master' of git://github.com/RainerKuemmerle/g2o