Corrected the size of interaction_rhs_mat. (The previous commit, r3461, had the wrong message - it should've said "Using option_count to determine whether we need to include the fluid-particle drag term." I probably need more sleep.) 
Corrected the size of interaction_rhs_mat. (The previous commit, r3461, had the wrong message - it should've said "Using option_count to determine whether we need to include the fluid-particle drag term." I probably need more sleep.) 

rjferrier/fluidity,jjo31/ATHAM-Fluidity,iakovos-panourgias/fluidity,jjo31/ATHAM-Fluidity,jrper/fluidity,iakovos-panourgias/fluidity,jjo31/ATHAM-Fluidity,jrper/fluidity,jrper/fluidity,rjferrier/fluidity,rjferrier/fluidity,jrper/fluidity,rjferrier/fluidity,iakovos-panourgias/fluidity,iakovos-panourgias/fluidity,jrper/fluidity,rjferrier/fluidity,jjo31/ATHAM-Fluidity,iakovos-panourgias/fluidity,jjo31/ATHAM-Fluidity