added pdb_chain splitter code and wrapper

scripts/chain_splitter.py

@@ -0,0 +1,28 @@
+#!/usr/bin/python3
+
+#=======================================================================
+# TASK: extract chain from pdb and save each chain as a separate file
+
+# link for saving each chain as a separate file
+#=======================================================================   
+__description__ = \
+"""
+pdb_chain_splitter.py
+
+extracts chains and saves them as separate pdb files.
+"""
+__author__ = "Tanushree Tunstall"
+__date__ = ""
+
+from Bio.PDB import Select, PDBIO
+from Bio.PDB.PDBParser import PDBParser
+
+class ChainSelect(Select):
+    def __init__(self, chain):
+        self.chain = chain
+
+    def accept_chain(self, chain):
+        if chain.get_id() == self.chain:
+            return 1
+        else:          
+            return 0