v2.6.4

Highlights:

• syntax
  • Support array elements without values, like declare -A x=([index]=)
  • Parse for i; do ... uniquely, as it's short for for i in "$@"
  • Add missing error on unclosed nested backquotes
• expand
  • Don't expand tildes twice, fixing echo ~ on Windows
• interp
  • Fix the use of Params as an option to New
  • Support lowercase Windows volume names in $PATH

Binaries built on go version go1.12 linux/amd64.