v2.2.1

Highlights:

• syntax
  • Don't error on ${1:-default}
  • Allow single quotes in ${x['str key']} as well as double quotes
  • Add support for ${!foo[@]}
  • Don't simplify foo[$x] to foo[x], to not break string indexes
  • Fix Stmt.End when the end token is the background operator &
  • Never apply the negation operator ! to && and || lists
  • Apply the background operator & to entire && and || lists
  • Fix StopAt when the stop string is at the beginning of the source
  • In N>word, check that N is a valid numeric literal
  • Fix a couple of crashers found via fuzzing
• cmd/shfmt
  • Don't error if non-bash files can't be written to

Binaries built on go version go1.9.3 linux/amd64.