b3CreateBoxCommandSetColorRGBA: allow to specify color when creating bodies through shared memory API

Parse and use colors from URDF file (single rgba color per link, not per visual)
Rename btMultiBody 'stepVelocities' to 'computeAccelerationsArticulatedBodyAlgorithmMultiDof'
btHashMap, add const Value* operator[]
remove a few more obsolete btMultiBody methods (on the non-multi-dof path)
fix spelling typo in fillConstraintJacobianMultiDof (fil -> fill)
Add mention to Jakub Stepien for his work on btMultiBody

examples/Importers/ImportURDFDemo/UrdfParser.cpp

@@ -346,6 +346,8 @@ bool UrdfParser::parseVisual(UrdfVisual& visual, TiXmlElement* config, ErrorLogg
 	  {
 		  if (parseMaterial(visual.m_localMaterial, mat,logger))
 		  {
+			  UrdfMaterial* matPtr = new UrdfMaterial(visual.m_localMaterial);
+			  m_model.m_materials.insert(matPtr->m_name.c_str(),matPtr);
 			  visual.m_hasLocalMaterial = true;
 		  }
 	  }
@@ -786,7 +788,7 @@ bool UrdfParser::loadUrdf(const char* urdfText, ErrorLogger* logger, bool forceF
 				for (int i=0;i<link->m_visualArray.size();i++)
 				{
 					UrdfVisual& vis = link->m_visualArray.at(i);
-					if (!vis.m_hasLocalMaterial)
+					if (!vis.m_hasLocalMaterial && vis.m_materialName.c_str())
 					{
 						UrdfMaterial** mat = m_model.m_materials.find(vis.m_materialName.c_str());
 						if (mat && *mat)