Misc. typos

+ some are doxy others are just comment code.  
+ some minor whitespace and grammatical tweaks. 
+ app/SCL/* typos have also been submitted upstream (https://github.com/stepcode/stepcode/pull/366). So it's ok to merge them in to master.

src/Gui/Quarter/QuarterWidget.cpp

@@ -450,7 +450,7 @@ QuarterWidget::clearWindow(void) const
 /*!
   Enable/disable interaction mode.
 
-  Specifies wether you may use the alt-key to enter interaction mode.
+  Specifies whether you may use the alt-key to enter interaction mode.
 */
 void
 QuarterWidget::setInteractionModeEnabled(bool onoff)

src/Gui/SoFCSelection.cpp

@@ -840,7 +840,7 @@ SoFCSelection::redrawHighlighted(SoAction *  action , SbBool  doHighlight )
 SbBool 
 SoFCSelection::readInstance  (  SoInput *  in, unsigned short  flags )
 {
-    // Note: The read in document name can be false, so the caller must ensure pointing to the correct documemt
+    // Note: The read in document name can be false, so the caller must ensure pointing to the correct document
     SbBool ret = inherited::readInstance(in, flags);
     return ret;
 }

src/Gui/iisTaskPanel/config.pri

@@ -15,7 +15,7 @@ CONFIG += debug_and_release
 macx {
         # Using gcc
         QMAKESPEC=macx-g++
-        # uncoment this line if you want use xcode
+        # uncomment this line if you want use xcode
         # QMAKESPEC=macx-xcode
 }