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/Mod/Assembly/Gui/TaskAssemblyConstraints.cpp

@@ -58,7 +58,7 @@ TaskAssemblyConstraints::TaskAssemblyConstraints(ViewProviderConstraint* vp)
     ui->setupUi(proxy);
     this->groupLayout()->addWidget(proxy);
 
-    //initialy hide the value and orientation field
+    //initially hide the value and orientation field
     ui->value_widget->hide();
     ui->orientation_widget->hide();