Responded to changes in tidyselect, eliminating warnings from several dplyr::all_of() invocations.
Defend against zero-row data frames, which can occur when there is no muscle work data. Now returning zero-row data frames to enable pipelines containing some countries without muscle work data.
prep_psut() now returns a zero-row data frame if the inputs are zero-row data frames.
New function phi_vec_mw() creates a phi vector for use when converting energy to exergy.
New functions to create a data frame of PSUT matrices representing a muscle work energy conversion chain. See prep_psut() and friends.
Functions now return uniform data frames with the following columns: AMW.Region.code (or HMW.Region.code), Country.code, Year, Species (or Sex), Stage, Sector, and E.dot.
MWTools 0.1.0
Added a NEWS.md file to track changes to the package.