Anchor propagation for ligatures is broken somtimes

Consider the font [JosefinSans.glyphs](https://github.com/ThomasJockin/JosefinSansFont-master/blob/master/sources/JosefinSans.glyphs); the glyph `f_ij` has two components `f` and `ij` and it ends up with the anchors `bottom`, `bottom_1`, `bottom_2`, `ogonek`, `top`, `top_1`, and `top_2`, but the `top` and `bottom` anchors make no sense here AFAIK. Even worse, the glyph `f_f_ij` ends with different set of anchors (name names but different positions) on each run.

Furthermore, I think the number of ligature anchors need to reflect the number of characters that make up the ligature not the number of components which may or may not be unrelated. i.e. if we have `sub f ij by f_ij;` then there should be two ligature anchors regardless of how many components `f_ij` glyph has.