lib: re-add partial image flag

And activate perimeter points removal if this flag is set

This flag should be set for aes1610, aesx660, aes2501, aes2550
and upektc_img since these sensors may produce incomplete image.

Fixes: #142

libfprint/drivers/aes1610.c

@@ -614,6 +614,7 @@ capture_read_strip_cb (FpiUsbTransfer *transfer, FpDevice *device,
       self->strips = g_slist_reverse (self->strips);
       fpi_do_movement_estimation (&assembling_ctx, self->strips);
       img = fpi_assemble_frames (&assembling_ctx, self->strips);
+      img->flags |= FPI_IMAGE_PARTIAL;
 
       g_slist_free_full (self->strips, g_free);
       self->strips = NULL;