v2.4.0

Changelog

736aaa1 Add decrypt command
0b2692a Add doc on detemining whether the machine is a laptop or desktop
ed65ef6 Add encrypt command
98b92c2 Add initial --use-builtin-age flag
dd116f7 Build with Go 1.17.1
63610a4 Extend init command to guess the user's username for private repos
34ecd67 Fix internal capitalization of age
da04181 Simplify internal use of auto bools
2ff4151 Update dependencies