header naming issue instrument <> instrumentName

[Markus Schneider]

Hallo all,

"Staff.instrument" was renamed to "Staff.instrumentName" in 2.9.14 but the
variable "instrument" in the header block remained unchanged. Since all
"instrument"-Variables of the header block are also renamed to
"instrumentName" by convert-ly, no instrument names will show after the
conversion.

Either the naming in the header block must be changed to reflect the current
changes (also to "instrumentName") or convert-ly has to pay attention to
that and omit these vars.

Markus