Release v0.12.6

• implement options for consuming remaining arguments (--args, --jsonargs, $ARGS.positional)
• fix delpaths function with overlapped paths
• fix --exit-status flag with halt, halt_error functions
• fix input_filename function with null input option
• fix path value validation for nan
• fix crash on branch optimization (if 0 then . else 0|0 end)
• add validation on regular expression flags to reject unsupported ones
• improve performance of range, join, flatten functions
• improve constant value optimization for object with quoted keys
• remove dependency on forked go-flags package