Removed obsolete code in implementation of #738
Implemented ticket #738 "'read' should optionally consider quotation marks"
Implemented ticket #743 "Create a function to calculate the weekday from a date"
Improved implementation of ticket #755
Implemented ticket #755 "File tree tooltips for procedures shall display the documentation"
fixed the issue where all "is_CHARTYPE" functions resulted in an error for empty strings, now the functions return FALSE for that case as detailed in ticket #752.
Implemented ticket #740 "Do not install already installed packages"
Implemented ticket #754 "Replace *.backup files with real *.revisions"
Implemented ticket #756 "New table method 'TAB().pearson()'"
Deletet already merged branch for ticket #702