Added 'txpMissing' slot to TxpResult; this stores information regarding the
amount of missing data in the dataset per slice
Added ggplot capabilities for plotting with several new aesthetics
Updated vignettes
Transferred maintainer to Jonathon F Fleming
toxpiR 1.2.0
Now require R>=4.0 due to reports of installation issues
Added 'txpValueNames' method for TxpModel
Added 'txpExportGui' function
Added 'TxpResultParam' object and 'txpResultParam' slot to TxpResult; this
stores the parameters controlling the calculation of the scores, e.g. the
rank ties method
Modified the log transformation functions within txpImportGui to match the
negative value handling behavior in the GUI