Removing libpng from ext and removed the libpng build command from the ext build target. Added the -DPNG_SKIP_SETJMP_CHECK flag to the linux2-config.py build config file. This should allow users to use their local copy of libpng rather than relying on the libpng in ext. Users should probably clean out their <fife>/etc/install/* directories and re-run 'scons ext'. Tested on ubuntu 10.04

lib_LTLIBRARIES = libguichan_allegro.la

INCLUDES = -I$(top_srcdir)/include

libguichan_allegro_la_LDFLAGS = -no-undefined -release $(LT_RELEASE) -version-info $(LT_CURRENT):$(LT_REVISION):$(LT_AGE)

libguichan_allegro_la_SOURCES =		\
		allegro.cpp		\
		allegrofont.cpp		\
		allegrographics.cpp	\
		allegroimage.cpp	\
		allegroimageloader.cpp	\
		allegroinput.cpp