templater: handle division by zero in arithmetic For now, just turn it to an abort.

templater: provide arithmetic operations on integers The termwidth template keyword is of limited use without some way to ensure that margins are respected. Provide a full set of arithmetic operators (four basic operations plus the mod function, defined to match Python's // for division), so that you can create termwidth based layouts that match the user's terminal size

eol: store and reuse pattern matchers instead of creating in tight loop More "right" and more efficient.