WE port: keyboard shortcuts: syntax mappings

[myrdd]

Tasks:

Both tasks refer to function _getKeyAttributesFromCombo(aCombo).

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Task 1: allow aCombo to be split by either (space) or + (plus sign)

• if the combo contains at least one plus sign:
  • split the combo by +
• else:
  • split the combo by (space), as it is done now

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Task 2: map WE command modifiers to XUL key modifiers

• mappings:
  • Ctrl -> accel (yes, sure!)
  • Alt -> alt
  • Command -> accel (I'm quite sure about this)
  • MacCtrl -> control
  • Shift -> shift
• put the mapping right before this for loop

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