Release v1.7.2

Package

• Fixed the attach-time version check so that it no longer leaves stale messages for up to a week

Models

• Fixed play_diffusions() so that it drops, with a warning, runs where nothing spreads beyond the seed,
  instead of stopping with "arguments imply differing number of rows"
• Set a seed in the test_fit() test so that it does not fail at random

Tutorials

• Updated intro tutorial
  • Added sections on types, missing data, indexing with [, [[, and $,
    changing data frames with mutate() and filter(), random numbers and seeds,
    reading errors and writing reproducible examples, and files and projects
  • Moved packages to a closing "Where next" section that points to the {manynet} tutorials
  • Replaced dead links, removed T/F shorthand, and fixed typos