* app/Makefile.am: added gimphistogram*, histogramwidget*,
	removed histogram.[ch]

	* app/histogram.[ch]: removed.  replaced with histogramwidget.[ch].

	* app/{gimphistogramP.h, gimphistogram.h, gimphistogram.c}: new
 	functions that calculate histograms in parallel and perform
 	calculations on them.

	* app/histogramwidget.[ch]: Same as old histogram.[ch], only it is
 	now a real widget, and it uses GimpHistograms instead of arrays of
 	values.

	* app/curves.c: #include gimphistogram.h instead of histogram.h.

	* app/equalize.c: use GimpHistogram and GimpLut.

	* app/gimpbrush.c, app/gimpimage.c, app/gimpset.c: use
	GTK_RUN_FIRST in calls to gimp_signal_new.

	* app/histogram_tool.c, app/levels.c, app/threshold.c: modified to
 	use the new HistogramWidget.

	* app/paint_funcs.c: removed some unused variables.

	* app/preferences_dialog.c: only display the num-processor field
 	if we are configured --with-mp

	* plug-ins/gee/gee.c: removed a couple of c++ style comments.