Major changes to CIA interpolation:
1) Add contribution from CH4 (H2-CH4,He-CH4,CH4-CH4) ;
2) Add some tests before interpolation for H2, He and CH4 ;
3) Add the possibility to choose between a normal or equilibrium ortho:para
fraction for CIA H2;
4) Change "strictboundH2H2cia" to the generic "strictboundcia" for H2,He,CH4.
It can be added for others CIA (N2,H,CO2...) if you want.