Staff line thickness scales with the size of the staff, but was not being set in gsp-default.tex. As a result, whenever the default spacings were loaded and the staff size wasn't currently set to the default, the line thickness would change. This change puts the setting of the staff line thickness into gsp-default so that it will scale as expected.
Fixes #1461
Staff line thickness scales with the size of the staff, but was not being set in gsp-default.tex. As a result, whenever the default spacings were loaded and the staff size wasn't currently set to the default, the line thickness would change. This change puts the setting of the staff line thickness into gsp-default so that it will scale as expected.