Part: activate Part_ColorPerFace in the menu and toolbar

According to the source this command was deactivated until issue #0477
and hence #1954 could be solved. However, since those issues
haven't been addressed the command has remained hidden for a long time.
This command does not work with objects that reimplement
their edit modes, meaning that it may work with Part and PartDesign
created objects but not with Draft and Arch objects.

The command is added to the standard `View` menu,
and to one `Part tools` toolbar so that it is no longer hidden.
The limitations of the command can be described in the documentation,
and then somebody else can help solve the problem
with the edit modes.

A new icon for the command is also provided.

src/Mod/Part/Gui/Workbench.cpp

@@ -158,7 +158,16 @@ Gui::MenuItem* Workbench::setupMenuBar() const
              << "Part_Measure_Toggle_Delta";
 
     // leave this for 0.14 until #0000477 is fixed
-#if 0
+
+    // According to #0477 and #1954
+    // `Part_ColorPerFace` does not work with objects that reimplement
+    // their edit modes, meaning it may work with Part and PartDesign
+    // created objects but not with Draft and Arch objects.
+    // However, it does not make much sense to keep it hidden;
+    // having it available in the interface will allow more people
+    // to use it, and maybe somebody will be able to investigate
+    // and fix the issue.
+#if 1
     Gui::MenuItem* view = root->findItem("&View");
     if (view) {
         Gui::MenuItem* appr = view->findItem("Std_RandomColor");
@@ -199,7 +208,8 @@ Gui::ToolBarItem* Workbench::setupToolBars() const
           << "Part_Sweep"
           << "Part_CompOffset"
           << "Part_Thickness"
-          << "Part_ProjectionOnSurface";
+          << "Part_ProjectionOnSurface"
+          << "Part_ColorPerFace";  // See issues #0477 and #1954 in the tracker
 
     Gui::ToolBarItem* boolop = new Gui::ToolBarItem(root);
     boolop->setCommand("Boolean");