The core logic around a terminal; it defines the base
through which anything (including basic cursor-navigation and typing)
interacts with the terminal.
Maintains basic invariants, such as "cursor should always be within the buffer", and "ansi terminal should reflect most up to date TermState"
Computes how tall a line of text is when wrapped at
Even 0-character lines still take up one row!
width = 2 0 -> 1 1 -> 1 2 -> 1 3 -> 2 4 -> 2 5 -> 3