Adding a more minimal ligature set

[neiios]

The README mentions that some ligatures are designed to reduce visual noise, while others help balance whitespace.

I propose adding an option to selectively disable ligatures that significantly alter the original characters, while still enabling those that improve whitespace.

For example:

• Disable: Ligatures that reduce visual noise:

  

• Enable: Ligatures that help balance whitespace:

  

Could this maybe be implemented as an additional stylistic set (like ss19), but affecting a wider range of ligatures?

Potentially related issues: #529, #588.