Changes to /f and /longs in italic fonts

[georgd]

/f and /longs:

• open the upper bow a little bit more
• Try rotating the stem back a bit: the original f stems were less slanted.
• Reduce the drop shape of the bow. The text size Garamonds show very little contrast there.

f- and longs-ligatures

• Reduce the width
• Re-implement ligatures with component glyphs. (Octavio already drew the component glyphs but they don't have their own slots yet).
  This is going to result in more glyphs than in the regular fonts because /f and /f.short can't be used as last component in a ligature and the same is valid for /i.dotless and /j.dotless.
• Keep Octavio's less stepped f_f design (First f's top bow is lower than the second f's but both bottom bows are at the same height) which is closer to the original. Perhaps implement the original open bottom here (the two bottom bows don't touch and leave a gap).
• Add variant glyphs for the more stepped version.

/longs

Some of Garamont's and Granjnon's italic longs have no bottom bow. Instead the stem descending the full descender depth is cut without any terminal feature like a bow or serif. For today's users this might look a bit weird, but it should be available as a character variant.

[georgd]

Glyphs to design:

• f before f: f._f
• f after f: f.f_
• short f after f: f.short.f_
• dotless i and j after f: i.dotless.f_ and j.dotless.f_
• t after f: t.f_
• f before letters with left ascender: f._ascender
• letters with left ascender after f: l._f, b._f, h._f, k._f, thorn._f