Added the read_ods_multsheets() function
Added a NEWS.md file to track changes to the package.
Edited find_col_info() to return a nice message instead of an error when there are no more invalid columns left to check.
Fixed an issue in read_multsheets() where the guess_max argument was not used if the file type was csv.
Added the plot_map() function to map the field layout of a single trial or all trials.