making HODLR solver recompute on kernel changes properly
making HODLR solver recompute on kernel changes properly

jbernhard/george,karenyyng/george,karenyyng/george,dfm/george,karenyyng/george,migueldvb/george,migueldvb/george,migueldvb/george,andres-jordan/george,jbernhard/george,dfm/george,andres-jordan/george,jbernhard/george,andres-jordan/george