start to refactor the rendering Previously each vline (visual line) had a full copy of its associated string, this changes it so it only slices a part of the parent line. Reduces significantly the memory usage. This actually worsen the emojify-link glitch reported by Freezr after the some recent refactoring in the wrapping code. Not a big deal since I'm about to restructure the whole rendering bit by bit (hopefully!)

typo

move some unicode-related code in u/