Update SDPD part
Merge branch 'roller' of github.com:qingguang/lammps-sph into roller

Conflicts:
	examples/USER/sph/sdpd-polymer-roller/2d-vars.lmp
	examples/USER/sph/sdpd-polymer-roller/run.sh
	examples/USER/sph/sdpd-polymer-roller/sdpd-polymer-run.lmp