BioCroField 0.4.0

• It is now possible to specify extra columns to be returned in the output from biomass_table.
• Values of time are now calculated using BioCro::add_time_to_weather_data to ensure they are always consistent with BioCro's time definition.
• Values of partitioned leaf mass can be set to NA when creating a harvest_point, which is treated as if the leaf mass had not been provided.