_root_zone_water being called inside functions

[thomasdkelly]

Through the line_profile test we can see a good chunk of time is being spend in the transpiration, canopy_cover, harvest index functions. These functions all call inner functions such as _root_zone_water which prevents us from AOT compiling them (#33 ). From a quick glance it appears as though _root_zone_water could instead be called just before these functions are called, with the _root_zone_water return arguments then being passed on to the transpiration/canopy cover function.