app: gimp_gegl_convolve() rename parameter "matrix" to "kernel"
app: use gimp_gegl_convolve() in gimpbrush-transform.c
gimpbucketfilltool: Fix switch block always falling through to pattern fill
app: remove CONSTRUCT_ONLY from "premultiplied" of GimpOperationPointLayerMode

not because we want to change it after construction, but because it is
ugly to avoid setting it again in the generic "configure mode node" code.
app: use gimp_gegl_node_set_layer_mode() to configure the FS' mode node
app: don't special case the FS wrt its visibility in the layer stack

Its source node produces nothingness anyway, so it can be safely
plugged in. More FS special code gone \o/.
app: fix mode node creation in gimp_gegl_create_apply_buffer_node()
plug-ins: port file-pat to GEGL, as a file plug-in example
app: simplify leftover and now useless nested if()
app: set the mode on the right node in gimp_gegl_create_apply_buffer_node()
app: fix non-premultiplied case in GimpOperationNormalMode
app: port gimp_drawable_real_apply_buffer() to GEGL

but leave the old code there and use it for FS compositing (when
dest_buffer is != NULL) because we need the legacy projection as
reference.
app: require a non-NULL format in gimp_tile_manager_create_buffer()
app: gimp_edit_paste(): use more formats inatead of GimpImageType
app: more consistent format handling in gimpdrawable-convert.c
app: fix drawable type check in gimp_drawable_convert_indexed()
app: add gimp_image_get_layer_format()
app: use gimp_image_get_layer_format() instead of dealing with image_type
app: don't use GIMP_IMAGE_TYPE_IS_FOO() in drawable_actions_update()
app: remove GimpImageType based API and macro junk