rewriting of the docu in AllGenerics.R;

changed column swapping in barplot.R;
changed page title of dimred_feature_page;
debugged wrapper of feature_expression_page;
subset_row is now obligatory in the heatmap;
removed double code block of plotly_violinplot in visualization_functions;
fixed small colormap bugs in barplot.Rmd, violinplot.Rmd and boxplot.Rmd;