Merge position-rotation-and-scale-intervals page into lerp-intervals

They cover the same intervals, a user got confused about the difference between these

Author: rdb

_static/redirects.json

@@ -2,6 +2,8 @@
     "programming/scene-graph/scene-graph-manipulations": "programming/scene-graph/model-files",
     "programming/models-and-actors/loading-models": "programming/scene-graph/model-files",
     "programming/models-and-actors/level-of-detail": "programming/scene-graph/level-of-detail",
+    "programming/intervals/position-rotation-and-scale-intervals": "programming/intervals/lerp-intervals",
+    "programming/tasks-and-events/global-clock": "reference/builtins#the-global-clock",
     "programming/text/index": "programming/gui/index",
     "programming/text/text-fonts": "programming/gui/text-fonts",
     "programming/text/text-node": "programming/gui/rendering-text",
@@ -24,7 +26,6 @@
     "programming/directgui/directscrolledframe": "programming/gui/directgui/directscrolledframe",
     "programming/timing/global-clock": "reference/builtins#the-global-clock",
     "programming/timing/index": "reference/builtins#the-global-clock",
-    "programming/tasks-and-events/global-clock": "reference/builtins#the-global-clock",
     "programming/math-engine/matrix-representation": "programming/internal-structures/matrix-representation",
     "programming/math-engine/index": "programming/internal-structures/matrix-representation",
     "programming/multifiles/index": "programming/advanced-loading/multifiles",

programming/intervals/index.rst

@@ -131,7 +131,6 @@ Table of Contents
    actor-intervals
    sound-intervals
    sequences-and-parallels
-   position-rotation-and-scale-intervals
    motion-paths
    particle-intervals
    projectile-intervals

programming/intervals/lerp-intervals.rst

@@ -118,6 +118,28 @@ the lerp.
       same name will automatically stop when this one is started. The default is
       to assign a unique name for each interval.
 
+   Convenience Short-Hands
+   -----------------------
+
+   Various convenience methods are defined on the NodePath class which provide
+   a short-hand syntax for creating a LerpInterval for that NodePath.
+   These are called ``posInterval()``, ``hprInterval()``, ``quatInterval``, and
+   so on. As an example:
+
+   .. code-block::
+
+      # This lets the actor move to point 10, 10, 10 in 1.0 second.
+      myInterval1 = myActor.posInterval(1.0, Point3(10, 10, 10))
+
+      # This move takes 2.0 seconds to complete.
+      myInterval2 = myActor.posInterval(2.0, Point3(8, -5, 10))
+
+      # You can specify a starting position, too.
+      myInterval3 = myActor.posInterval(1.0, Point3(2, -3, 8), startPos=Point3(2, 4, 1))
+
+      # This rotates the actor 180 degrees on heading and 90 degrees on pitch.
+      myInterval4 = myActor.hprInterval(1.0, Vec3(180, 90, 0))
+
    The rest of the NodePath-based LerpIntervals
    --------------------------------------------