Misc. typos

Found via `codespell -q 3`

src/ifcconvert/IfcConvert.cpp

@@ -257,7 +257,7 @@ int main(int argc, char** argv)
             "Not guaranteed to work properly if used with --weld-vertices.")
         ("filter-file", po::value<std::string>(&filter_filename),
             "Specifies a filter file that describes the used filtering criteria. Supported formats "
-            "are '--include=arg GlobalId ...' and 'include arg GlobalId ...'. Spaces and tabs can be used as delimeters."
+            "are '--include=arg GlobalId ...' and 'include arg GlobalId ...'. Spaces and tabs can be used as delimiters."
             "Multiple filters of same type with different values can be inserted on their own lines. "
             "See --include, --include+, --exclude, and --exclude+ for more details.");
 

src/ifcconvert/XmlSerializer.cpp

@@ -464,7 +464,7 @@ void XmlSerializer::finalize() {
 
     // Layer assignments. IfcPresentationLayerAssignments don't have GUIDs (only optional Identifier)
     // so use names as the IDs and only insert those with unique names. In case of possible duplicate names/IDs
-    // the first IfcPresentationLayerAssignment occurence takes precedence.
+    // the first IfcPresentationLayerAssignment occurrence takes precedence.
     std::set<std::string> layer_names;
     IfcPresentationLayerAssignment::list::ptr layer_assignments = file->entitiesByType<IfcPresentationLayerAssignment>();
     for (IfcPresentationLayerAssignment::list::it it = layer_assignments->begin(); it != layer_assignments->end(); ++it) {