Returns the ending position of a given paragraph. Paragraphs are numbered starting with 0.
Calling this method may force the recalculation of location information if a maximum width is set for the editor, even if the editor currently has delayed refreshing (see refresh-delayed?). If the editor is not displayed and the editor has a maximum width, line breaks are calculated as for line-start-position.
If there are fewer than paragraph-1 paragraphs, the end of the last paragraph is returned. If paragraph is less than 0, then the end of the first paragraph is returned.
If the paragraph ends with invisible items (such as a carriage return) and visible? is not #f, the first position before the invisible items is returned.