Segfault when removing a cylinder

[Gaetan Bisson]

Dear all,

With current git master I'm consistently getting a segfault when trying
to remove a row from the Cylinders table in the Equipment tab, simply by
clicking on the trash bin icon.

The segfault occurs inside CylindersModel::remove(). I do not understand
much of that code but what I could piece together is the following:

- index.row() is +1 until the call to endRemoveRows()
- index.row() becomes -1 after the call to endRemoveRows()
- std::iota() then segfaults because its second argument is smaller than its first

Let me know if there's anything I could help test to fix this.

Cheers.

-- 
Gaetan