print better error warning, in case the physics client/server version mismatch.

fix in b3HashString
remove many unused dependencies from kuka_grasp_block_playback.py (time,math, datetime ,numpy,pylab ,sys, os, fnmatch,argparse were not used!)
move block_grasp_log.bin from Bullet3/data to Bullet3/examples/pybullet/examples/data folder.
PhysicsServerCommandProcessor, derive from CommandProcessorInterface to prepare for different back-end implementation

src/Bullet3Common/b3HashMap.h

@@ -44,8 +44,8 @@ struct b3HashString
 
 		/* Fowler / Noll / Vo (FNV) Hash */
 		unsigned int hash = InitialFNV;
-		
-		for(int i = 0; m_string[i]; i++)
+		int len = m_string.length();
+		for(int i = 0; i<len; i++)
 		{
 			hash = hash ^ (m_string[i]);       /* xor  the low 8 bits */
 			hash = hash * FNVMultiple;  /* multiply by the magic number */