Revert "Revert "Remove Parser fallback code""

This reverts commit fcfcfe178cb7579e3a4ede1523c6ee982efcb928.
[Fix #1141] Clarify why trailing comma is not allowed

For lists where some values share a line it is unclear why a comma
is not allowed, unless we state it in the message.
Merge pull request #1150 from jonas054/1141_clarify_trailing_comma

[Fix #1141] Clarify why trailing comma is not allowed
Bump parser dep to 2.2.0.pre.2