Split up PreferencesUI.py into individual files for each class, then fixed the imports everywhere that broke because of this.

flatcamGUI/preferences/__init__.py

@@ -0,0 +1,17 @@
+from flatcamGUI.GUIElements import *
+import gettext
+import FlatCAMTranslation as fcTranslate
+import builtins
+
+
+
+fcTranslate.apply_language('strings')
+if '_' not in builtins.__dict__:
+    _ = gettext.gettext
+
+settings = QSettings("Open Source", "FlatCAM")
+if settings.contains("machinist"):
+    machinist_setting = settings.value('machinist', type=int)
+else:
+    machinist_setting = 0
+