[PLAT-6671] Removing interpolation when there is compounding

At this point it is not possible to interpolate when there are multiple compounding periods without the interpolation occuring on all compounding periods, when the interpolation should be only for the stub period
[PLAT-6671] Stub period interpolation doc update

Documenting the limitation to stub period interpolation when there is compounding on the leg
[PLAT-6671] Better performance in ArgumentChecker
Merge pull request #135 from OpenGamma/topic/PLAT-6671

[PLAT-6671] Removing interpolation when there is compounding