0.2.0
	'..tables' now returns an empty vector when there is no table in environment
	consequently all '!is.null' on input$main.data have to be replaced by '..isNotEmpty'.
	Added a parameter to remove the creation of example tables.
	BUGS:
	*	contents	displays only the 1st class
		view		1st dropdownbutton when no table: invalid 1st argument
		browse		1st dropdownbutton when no table, selecting columns by name: invalid 1st argument
		tabular		after deleting table: invalid 1st argument
		distinct	when no table: message from ..try
		edit		button 'validate' doesn't change of state
		graphics,	making a graphic (e.g. pie) then deleting used table leaves:
		tabular				<text>:1:2: SPECIAL inattendu(e)
						1:  %>%
	***	gather		transposing all variables of 'enquête' crashed IGoR (once)
 
	TODO:
		mutate2		use the same table of functions as in 'mutate'
	