Modified to unit test, that when model:
MODEL_PARAMS_NS_R1RHO_3SITE
nest from: MODEL_PARAMS_NS_R1RHO_2SITE
the conversion should be: 'r2', 'r2' 'pA', 'pA' 'dw_AB', 'dw' 'kex_AB', 'kex' 'pB', '1 - pA' 'dw_BC', 'dw' 'kex_BC', 'kex' 'kex_AC', 'kex'
Here '1 - pA' is a special conversion flag.
Authored by: tlinnet 2014-08-20
Parent: [r25120]
Child: [r25122]
