Store all results of the examples run by ctest in their own unique subdirectory of the build tree.  This keeps the plplot_test subdirectory much cleaner, and makes it easy to implement a clean and quick way to remove all those ctest-generated files.
Store all results of the examples run by ctest in their own unique
subdirectory of the build tree.  This keeps the plplot_test
subdirectory much cleaner, and makes it easy to implement a clean
and quick way to remove all those ctest-generated files.

This change solves two bugs with the old method of removing all the
generated files using a list of filenames; that method was inexact
(the list of filenames was incomplete) and more seriously also ran
into command-line length issues for the cmd environment used for the
"MinGW Makefiles" generator case.


svn path=/trunk/; revision=13123

FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot