[MIDI import] Heading names for track panel

The track panel for MIDI import lists the following headings:

• Track
• Import?
• Name
• Instrument

There has been some confusion from early testers about the meaning of and distinction between "Name" and "Instrument"---particularly "Name" since the column is often blank. I wonder if the words "Staff Name" and "Sound" would be clearer? "Sound" would also match the corresponding label in View > Mixer.

The order of the "Track" and "Import" columns seems backwards, since the convention for checkboxes is to be at the start of a line (or occasionally the end of a line). I don't remember seeing a checkbox in the middle of a line before.

Finally, the question mark in "Import?" looks odd to me. I suggest dropping it.

Here's my proposal for the wording and order of the headings:

• Import
• Track
• Staff Name
• Sound

MuseScore version: e56b82d

(Operating System: Windows 7)