Add help for ParallelStacks Visualizer

.gitignore

@@ -1 +1,2 @@
 icons/
+.swp

src/SeerParallelStacksVisualizerWidget.cpp

@@ -60,7 +60,7 @@ void SeerParallelStacksVisualizerWidget::handleRefreshButton () {
 void SeerParallelStacksVisualizerWidget::handleHelpButton () {
 
     SeerHelpPageDialog* help = new SeerHelpPageDialog;
-    help->loadFile(":/seer/resources/help/ImageVisualizer.md");
+    help->loadFile(":/seer/resources/help/ParallelStacksVisualizer.md");
     help->show();
     help->raise();
 }

src/resource.qrc

@@ -67,6 +67,7 @@
     <file>resources/help/ArrayVisualizer.md</file>
     <file>resources/help/MatrixVisualizer.md</file>
     <file>resources/help/ImageVisualizer.md</file>
+    <file>resources/help/ParallelStacksVisualizer.md</file>
     <file>resources/help/StackInfoBrowser.md</file>
     <file>resources/help/VariableRegisterInfoBrowser.md</file>
     <file>resources/help/SourceSymbolLibraryInfoBrowser.md</file>

src/resources/help/ParallelStacksVisualizer.md

@@ -0,0 +1,33 @@
+## ParallelStacks Visualizer
+
+### Introduction
+
+The ParallelStacks Visualizer shows all the thread's stack frames as a node graph. Currently this is a static image. Future plans
+are to make it dynamic in that thread nodes can be interacted with to tell Seer to switch to different threads and a frames within
+that thread.
+
+This Visualizer is taken from a feature of VSCode.
+
+### Refresh
+
+This will refresh the image since the last time.
+
+### Auto mode
+
+This mode will refresh the image each time Seer reaches a stopping point (when you 'step' or 'next' or reach a 'breakpoint'). Note,
+this can be costly.
+
+### ParallelStacks interaction
+
+Available Quick keys while in the ParallelStacks Visualizer:
+```
+    '+'   zoom in
+    '-'   zoom out
+    ESC   reset to default zoom level.
+```
+
+### Resources
+
+[Seer Issue](https://github.com/epasveer/seer/issues/312)  
+[GDB python script](https://github.com/bravikov/parallel-stacks)  
+