prj.ads, prj.adb: (Project_Data): Add new component Display_Name

2005-03-29  Vincent Celier  <celier@adacore.com>

	* prj.ads, prj.adb: (Project_Data): Add new component Display_Name

	* prj-part.adb (Parse_Single_Project): Set the location of a project
	on its defining identifier, rather than on the reserved word "project".

	* prj-proc.adb (Expression): Adapt to the fact that default of external
	references may be string expressions, not always literal strings.
	(Recursive_Process): Set Display_Name equal to Name
	when Location is No_Location, that is when there is no actual file.
	Get the Display_Name of the project from the source, when it is not a
	virtual project.
	(Process): Use the Display_Name in error messages

	* prj-strt.adb (External_Reference): Allow default to be string
	expressions, not only literal strings.

From-SVN: r97180