Add the 'between' invalidation strategy for markers

This invalidates markers when the start or end point of the changed 
range is between the head and tail position of the marker.

src/app/buffer-marker.coffee

@@ -8,9 +8,10 @@ class BufferMarker
   headPosition: null
   tailPosition: null
   suppressObserverNotification: false
-  invalidationStrategy: 'contains'
+  invalidationStrategy: null
 
   constructor: ({@id, @buffer, range, @invalidationStrategy, noTail, reverse}) ->
+    @invalidationStrategy ?= 'contains'
     @setRange(range, {noTail, reverse})
 
   setRange: (range, options={}) ->
@@ -71,23 +72,30 @@ class BufferMarker
     newTailPosition = @getTailPosition()
     @notifyObservers({oldTailPosition, newTailPosition, bufferChanged: false})
 
-  tryToInvalidate: (oldRange) ->
-    containsStart = oldRange.containsPoint(@getStartPosition(), exclusive: true)
-    containsEnd = oldRange.containsPoint(@getEndPosition(), exclusive: true)
-    return unless containsEnd or containsStart
+  tryToInvalidate: (changedRange) ->
+    betweenStartAndEnd = @getRange().containsRange(changedRange, exclusive: false)
+    containsStart = changedRange.containsPoint(@getStartPosition(), exclusive: true)
+    containsEnd = changedRange.containsPoint(@getEndPosition(), exclusive: true)
 
-    if @invalidationStrategy is 'never'
-      previousRange = @getRange()
-      if containsStart and containsEnd
-        @setRange([oldRange.end, oldRange.end])
-      else if containsStart
-        @setRange([oldRange.end, @getEndPosition()])
-      else
-        @setRange([@getStartPosition(), oldRange.start])
-      [@id, previousRange]
-    else
-      @invalidate()
-      [@id]
+    switch @invalidationStrategy
+      when 'between'
+        if betweenStartAndEnd or containsStart or containsEnd
+          @invalidate()
+          [@id]
+      when 'contains'
+        if containsStart or containsEnd
+          @invalidate()
+          [@id]
+      when 'never'
+        if containsStart or containsEnd
+          previousRange = @getRange()
+          if containsStart and containsEnd
+            @setRange([changedRange.end, changedRange.end])
+          else if containsStart
+            @setRange([changedRange.end, @getEndPosition()])
+          else
+            @setRange([@getStartPosition(), changedRange.start])
+          [@id, previousRange]
 
   handleBufferChange: (bufferChange) ->
     @consolidateObserverNotifications true, =>

src/app/range.coffee

@@ -57,7 +57,11 @@ class Range
     else
       otherRange.intersectsWith(this)
 
-  containsPoint: (point, { exclusive } = {}) ->
+  containsRange: (otherRange, {exclusive} = {}) ->
+    { start, end } = Range.fromObject(otherRange)
+    @containsPoint(start, {exclusive}) and @containsPoint(end, {exclusive})
+
+  containsPoint: (point, {exclusive} = {}) ->
     point = Point.fromObject(point)
     if exclusive
       point.isGreaterThan(@start) and point.isLessThan(@end)