Bug 589371 - some new brushes.

Extract of a selection by Jose Americo Gobbo.
Reviewed by Aryeom and myself for integration.

From what I could gather, authors are:
- Grunge 01 by Rene Jensen.
- Stone Work 01 by Mathias Jonathan (Griffeur).
- Pencil 03 and Charcoal 03 by Americo.

According to information from Americo, all data is GPL v3.0.

data/brushes/Sketch/Makefile.am

@@ -8,8 +8,10 @@ brushsketchdata_DATA = \
 	Chalk-03.gih		\
 	Charcoal-01.gbr		\
 	Charcoal-02.gbr		\
+	Charcoal-03.gih		\
 	Pencil-01.gih		\
 	Pencil-02.gih		\
+	Pencil-03.gih		\
 	Pencil-Scratch.gbr
 
 EXTRA_DIST = $(brushsketchdata_DATA)

data/brushes/Splatters/Makefile.am

@@ -3,6 +3,7 @@
 brushsplattersdatadir = $(gimpdatadir)/brushes/Splatters
 
 brushsplattersdata_DATA = \
+	Grunge-01.gih	\
 	Sparks-Hose.gih	\
 	Splats-01.gih	\
 	Splats-02.gih	\

data/brushes/Texture/Makefile.am

@@ -6,7 +6,9 @@ brushtexturedata_DATA = \
 	Cell-01.gbr		\
 	Cell-02.gbr		\
 	Grass.gih		\
+	Hatch-Pen-01.gbr	\
 	Smoke.gbr		\
+	Stone-Work-01.gih	\
 	Structure.gbr		\
 	Texture-01.gbr		\
 	Texture-02.gbr		\