v1.9.0

• New functions add_prefix() and add_suffix() to add prefixes and suffixes to variable names, respectively.
• New function select_pred() to selects a best subset of predictor variables.
• New function acv() to compute the adjusted coefficient of variation to account for the systematic dependence of variance on mean.
• New function ge_acv() to compute yield stability index based on the adjusted coefficient of variation.
• New function ge_polar() to compute yield stability index based on Power Law Residuals (POLAR) statistics.
• New function mantel_test() to performs a Mantel test between two matrices.
• New arguments prefix and suffix in concatenate() to add prefixes and suffixes to concatenated values, respectively.
• List packages providing the Rd macros in 'Imports' instead of 'Suggests' as suggested by the CRAN team.