Port `BentShape` rebar to QT5

[amrit3701]

After selecting face of structure element, when user click on BentShape rebar button, it gives below error:

Running the Python command 'Arch_Rebar_BentShape' failed:
Traceback (most recent call last):
  File "/Users/amritpal/Library/Preferences/FreeCAD/Mod/FreeCAD-Reinforcement/RebarTools.py", line 120, in Activated
    BentShapeRebar.CommandBentShapeRebar()
  File "/Users/amritpal/Library/Preferences/FreeCAD/Mod/FreeCAD-Reinforcement/BentShapeRebar.py", line 362, in CommandBentShapeRebar
    FreeCADGui.Control.showDialog(_BentShapeRebarTaskPanel())
  File "/Users/amritpal/Library/Preferences/FreeCAD/Mod/FreeCAD-Reinforcement/BentShapeRebar.py", line 116, in __init__
    self.form.orientation.addItems(["Bottom", "Top", "Right", "Left"])

'builtin_function_or_method' object has no attribute 'addItems'Traceback (most recent call last):

This error because of PyQt5. In PyQt5 orientation object has no addItems attribute. You may take help of other rebars to fix this.

FreeCAD detail:

OS: macOS 10.14
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.18.Unknown
Build type: Release
Python version: 3.6.6
Qt version: 5.6.2
Coin version: 4.0.0a
OCC version: 7.3.0
Locale: English/India (en_IN)