Surface, MeshPart: update CurveOnMesh command tooltip and task panel

* Add new icon `MeshPart_CurveOnMesh`, which is the same as
the `Surface_CurveOnMesh` icon but in green color.
The surface icon is used in the Surface Workbench, while the MeshPart
version is currently not used.
* Make the tooltip of the command shorter; the longer instructions
are added in the `TaskCurveOnMesh` task panel.

src/Mod/MeshPart/Gui/Command.cpp

@@ -311,17 +311,11 @@ CmdMeshPartCurveOnMesh::CmdMeshPartCurveOnMesh()
     sAppModule    = "MeshPart";
     sGroup        = QT_TR_NOOP("Mesh");
     sMenuText     = QT_TR_NOOP("Curve on mesh...");
-    sToolTipText  = QT_TR_NOOP("Creates an approximated curve on top of the selected mesh.\n"
-                               "Press 'Start', then pick points on the mesh; "
-                               "when enough points have been set,\n"
-                               "right-click and choose 'Create'.\n"
-                               "\n"
-                               "This command only works with a 'mesh' object, "
-                               "not a regular face or surface.\n"
-                               "To convert an object to a mesh "
-                               "use the tools of the Mesh Workbench.");
+    sToolTipText  = QT_TR_NOOP("Creates an approximated curve on top of a mesh.\n"
+                               "This command only works with a 'mesh' object.");
     sWhatsThis    = "MeshPart_CurveOnMesh";
     sStatusTip    = sToolTipText;
+    sPixmap       = "MeshPart_CurveOnMesh";
 }
 
 void CmdMeshPartCurveOnMesh::activated(int)

src/Mod/MeshPart/Gui/Resources/MeshPart.qrc

@@ -1,8 +1,11 @@
 <RCC>
-    <qresource> 
+    <qresource>
         <file>icons/actions/MeshFace.svg</file>
+        <file>icons/MeshPart_CurveOnMesh.svg</file>
         <file>icons/MeshPart_Create_Flat_Face.svg</file>
         <file>icons/MeshPart_Create_Flat_Mesh.svg</file>
+    </qresource>
+    <qresource>
         <file>translations/MeshPart_af.qm</file>
         <file>translations/MeshPart_de.qm</file>
         <file>translations/MeshPart_fi.qm</file>
@@ -41,4 +44,5 @@
         <file>translations/MeshPart_ar.qm</file>
         <file>translations/MeshPart_vi.qm</file>
     </qresource>
-</RCC> 
+</RCC>
+

src/Mod/MeshPart/Gui/TaskCurveOnMesh.ui

@@ -6,8 +6,8 @@
    <rect>
     <x>0</x>
     <y>0</y>
-    <width>343</width>
-    <height>305</height>
+    <width>507</width>
+    <height>637</height>
    </rect>
   </property>
   <property name="windowTitle">
@@ -15,6 +15,24 @@
   </property>
   <layout class="QGridLayout" name="gridLayout_3">
    <item row="0" column="0" colspan="2">
+    <widget class="QGroupBox" name="groupBox_3">
+     <layout class="QVBoxLayout" name="verticalLayout">
+      <item>
+       <widget class="QLabel" name="lb_instructions">
+        <property name="text">
+         <string>Press 'Start', then pick points on the mesh; when enough points have been set, right-click and choose 'Create'. Repeat this process to create more splines. Close this task panel to complete the operation.
+
+This command only works with a 'mesh' object, not a regular face or surface. To convert an object to a mesh use the tools of the Mesh Workbench.</string>
+        </property>
+        <property name="wordWrap">
+         <bool>true</bool>
+        </property>
+       </widget>
+      </item>
+     </layout>
+    </widget>
+   </item>
+   <item row="1" column="0" colspan="2">
     <widget class="QGroupBox" name="groupBox">
      <property name="title">
       <string>Wire</string>
@@ -63,7 +81,7 @@
      </layout>
     </widget>
    </item>
-   <item row="1" column="0" colspan="2">
+   <item row="2" column="0" colspan="2">
     <widget class="QGroupBox" name="groupBox_2">
      <property name="title">
       <string>Spline Approximation</string>
@@ -129,14 +147,14 @@
      </layout>
     </widget>
    </item>
-   <item row="2" column="0">
+   <item row="3" column="0">
     <widget class="QPushButton" name="startButton">
      <property name="text">
       <string>Start</string>
      </property>
     </widget>
    </item>
-   <item row="2" column="1">
+   <item row="3" column="1">
     <spacer name="horizontalSpacer">
      <property name="orientation">
       <enum>Qt::Horizontal</enum>

src/Mod/Surface/Gui/Command.cpp

@@ -198,15 +198,8 @@ CmdSurfaceCurveOnMesh::CmdSurfaceCurveOnMesh()
     sAppModule    = "MeshPart";
     sGroup        = QT_TR_NOOP("Surface");
     sMenuText     = QT_TR_NOOP("Curve on mesh...");
-    sToolTipText  = QT_TR_NOOP("Creates an approximated curve on top of the selected mesh.\n"
-                               "Press 'Start', then pick points on the mesh; "
-                               "when enough points have been set,\n"
-                               "right-click and choose 'Create'.\n"
-                               "\n"
-                               "This command only works with a 'mesh' object, "
-                               "not a regular face or surface.\n"
-                               "To convert an object to a mesh "
-                               "use the tools of the Mesh Workbench.");
+    sToolTipText  = QT_TR_NOOP("Creates an approximated curve on top of a mesh.\n"
+                               "This command only works with a 'mesh' object.");
     sWhatsThis    = "Surface_CurveOnMesh";
     sStatusTip    = sToolTipText;
     sPixmap       = "Surface_CurveOnMesh";