Support lowercase 'ns' and 'ni' obj material tokens

Previously, the obj material parser would interpret all key tokens
starting with 'n' as 'newmtl' tokens. However, there are other tokens
that can start with 'n', namely 'ns' and 'ni' for material properties.
Make the parser robust to such cases, despite their canonical forms
being uppercase.

Resolves #410.

code/ObjFileMtlImporter.cpp

@@ -166,25 +166,27 @@ void ObjFileMtlImporter::load()
 			}
 			break;
 
-		case 'N':	// Shineness
+		case 'N':
+		case 'n':
 			{
 				++m_DataIt;
-				switch(*m_DataIt) 
+				switch(*m_DataIt)
 				{
-				case 's':
+				case 's':	// Specular exponent
 					++m_DataIt;
 					getFloatValue(m_pModel->m_pCurrentMaterial->shineness);
 					break;
-				case 'i': //Index Of refraction 
+				case 'i':	// Index Of refraction
 					++m_DataIt;
 					getFloatValue(m_pModel->m_pCurrentMaterial->ior);
 					break;
+				case 'e':	// New material
+					createMaterial();
+					break;
 				}
 				m_DataIt = skipLine<DataArrayIt>( m_DataIt, m_DataItEnd, m_uiLine );
-				break;
 			}
 			break;
-		
 
 		case 'm':	// Texture
 		case 'b':   // quick'n'dirty - for 'bump' sections
@@ -194,13 +196,6 @@ void ObjFileMtlImporter::load()
 			}
 			break;
 
-		case 'n':	// New material name
-			{
-				createMaterial();
-				m_DataIt = skipLine<DataArrayIt>( m_DataIt, m_DataItEnd, m_uiLine );
-			}
-			break;
-
 		case 'i':	// Illumination model
 			{
 				m_DataIt = getNextToken<DataArrayIt>(m_DataIt, m_DataItEnd);