Fix compatibility with Python 3

- Import "collections" correctly depending on the version of
Python
- Fix regex that raised deprecation warnings in Python 3

meshroom/core/attribute.py

@@ -37,7 +37,7 @@ def attributeFactory(description, value, isOutput, node, root=None, parent=None)
 class Attribute(BaseObject):
     """
     """
-    stringIsLinkRe = re.compile('^\{[A-Za-z]+[A-Za-z0-9_.]*\}$')
+    stringIsLinkRe = re.compile(r'^\{[A-Za-z]+[A-Za-z0-9_.]*\}$')
 
     def __init__(self, node, attributeDesc, isOutput, root=None, parent=None):
         """

meshroom/ui/reconstruction.py

@@ -3,7 +3,6 @@ import logging
 import math
 import os
 from threading import Thread
-from collections import Iterable
 
 from PySide2.QtCore import QObject, Slot, Property, Signal, QUrl, QSizeF
 from PySide2.QtGui import QMatrix4x4, QMatrix3x3, QQuaternion, QVector3D, QVector2D
@@ -14,6 +13,7 @@ from meshroom import multiview
 from meshroom.common.qt import QObjectListModel
 from meshroom.core import Version
 from meshroom.core.node import Node, CompatibilityNode, Status, Position
+from meshroom.core.pyCompatibility import Iterable
 from meshroom.ui.graph import UIGraph
 from meshroom.ui.utils import makeProperty