3.3.3 Date and DateTime, duplication

Split 3.3.3 Date and DateTime into 3.3.2 Date (before then 3.3.3 Time) and then 3.3.4 DateTime. Move all date related material to then 3.3.2 Date. After "Date is a subtype of Number." add "Date is represented by an integer value." Replace "A serial date is the expression of a date as the number of days elapsed from a start date. The start date for calculation of the serial form of a date is called an epoch. the number is the number of days from a particular date called the epoch." with "A serial date is the expression of a date as the number of days elapsed from a start date called the epoch." In then 3.3.4 DateTime say "DateTime is a subtype of Number. It is a Date plus Time." Reference for then 3.3.4 "DateAndDateTime" needs to be changed and maybe split into then 3.3.3 "Date" and 3.3.4 "DateTime", depending on usage in the rest of the document, and places referring need to be adapted.