check for non-existent image names from moonlib/image

Remove commented out configure flags for Gem
Try using $(DESTDIR) for Gem's --with-pd flag to find binary and header(s)

This can happen when one of ggee/image's display methods is called from a [loadbang]

[image] will throw an error "old command"

This shouldn't break any uses of moonlib/image. (Using the default image is actually an error in moonlib/image)

make accessors for cached image data in GUI (to be used by draw image, ggee/image, and moonlib/image)
revise drawimage code to use the accessors

more whitespace cleanup, comment and improve image_get_filename code so it doesn't look like a crasher bug

custom comment width not respected when editing
update css property word-wrap to overflow-wrap

vsl freezes after updating maximum-range in the dialog