templater: factor out runtemplate method As a side-effect, this makes the output of runmap non-flattened

templating: make new-style templating features work with command line lists

formatter: improve implementation of data method This alternate syntax was proposed by Bryan O'Sullivan in a review of 772b3764d3e8. I haven't been able to measure any particular performance difference, but the new syntax is more concise and easier to read.

Merge with crew-stable