Add iconic ligatures

[pelson]

Clearly TI is regularly in a ligatured form, for example in equation: https://xkcd.com/2034/

In the handwriting sample itself we have TI and TH both in nice ligatures.

[panda667]

Does the TR count as well? [zoomed image of "Truly" in bottom right corner of "All Truly Deep Physics Equations"]

You can see the arm of the T goes over the stem of the R and a little bit of the Rs bowl as well.