Split PowerShell root into two states, so we know when a close paren is expected.
Split PowerShell root into two states, so we know when a close paren is
expected.

Fixes #869

pathawks/pygments,pathawks/pygments,pathawks/pygments,pathawks/pygments,pathawks/pygments,pathawks/pygments,pathawks/pygments,pathawks/pygments,pathawks/pygments,pathawks/pygments,pathawks/pygments,pathawks/pygments,pathawks/pygments,pathawks/pygments,pathawks/pygments,pathawks/pygments