R/PEC_sw_drainage_UK.R: Create a function drainage_date_UK that does not only respect the beginning of the drainage period on 1 October, but also the end of the drainage period on 30 April, and use it for determining the degradation time. Applications early in the year before 1 May will now correctly be calculated without degradation time.
R/PEC_sw_drift.R: Vectorise the function not only with respect to distances, rates and water depths, but also with respect to crop groups. Closes issue #2 reported by Julian Klein (@juklei).
R/PEC_sw_drainage_uk.R: Fix a bug preventing the function to work of latest_application is set to 29 February. Also, make this function correctly deal with units.
R/twa.R: Fix a bug in plotting one-box models of class one_box that affected plots that displayed a time weighted average.
R/PEC_sw_drainage_uk.R: Fix a bug leading to increased PEC values in the case the application date is after the beginning of the drainage period and soil_DT50 was specified.
R/{PEC_sw_drift,PEC_sw_exposit_runoff,PEC_sw_sed}.R: Make use of the units package.
R/PEC_sw_drift.R: Change argument name from 'crop_group_focus' to 'crop_group_RF', in order to make it easier to understand the relation to the 'drift_data' argument.