Use run a 2D linear interpolation with interaction matrix to
calculate system capacity.
     
    
    Usage
    interaction_matrix_sys_cap(MInt, sc.dose.df, adult_sys_cap)
 
    
    Arguments
    - MInt
- One item from object returned from StressorResponseWorkbook() 
- sc.dose.df
- Data frame with columns HUC, Stressor, simulation, dose
and sys.cap. 
- adult_sys_cap
- Should the Joe Model be run only with variables
identified for adult system capacity. 
 
    
    Details
    Runs through an individual MInt_ worksheet object supplied from
sr_wb_dat$MInt and calculates system capacity. interaction_matrix_sys_cap()
should be run with apply on sr_wb_dat$MInt. Returns sc.dose.df with updated
system capacity and filtered for variables.