update comments for homogeneous_halfspace README (github test)
Merge branch 'devel' of git://github.com/geodynamics/specfem3d into devel
added a stop statement if the first time step entered by the user is negative
Merge branch 'devel' of git://github.com/geodynamics/specfem3d into devel
added Can Kangchen Bai to the list of developers
changed Can Kangchen Bai to Kangchen Bai
Merge branch 'devel' of git://github.com/geodynamics/specfem3d into devel
Conflicts temporary commented