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/App/PropertyExpressionEngine.cpp

@@ -731,7 +731,7 @@ std::string PropertyExpressionEngine::validateExpression(const ObjectIdentifier
     // Get document object
     DocumentObject * pathDocObj = usePath.getDocumentObject();
 
-    // Check for document object dependecies
+    // Check for document object dependencies
     for (std::set<App::ObjectIdentifier>::const_iterator j = exprDeps.begin(); j != exprDeps.end(); ++j) {
         DocumentObject * docObj = (*j).getDocumentObject();