Adding script to generate element blocks

Move generate element blocks script to contri/elements-dev-tools/

Fixing bug with not specifying datadir for generate element blocks script

Adding python docs, adding python env

Fixing indents issue on comment

contrib/elements-devtools/generate_element_blocks.py

@@ -0,0 +1,39 @@
+#!/usr/bin/env python3
+
+import os
+import subprocess 
+import json
+import argparse
+
+def sign_block(datadir):
+    """
+    Gets a new blocks hex, generates a signature for that block,
+    then submits the signed block to the running elementsd
+    """
+    bc=["./elements-cli", "-regtest"]
+    if datadir is not None:
+        bc.append("-datadir=" + datadir)
+    new_block = subprocess.check_output(bc + ["getnewblockhex"]).strip('\n')
+    blocksig = subprocess.check_output(bc + ["signblock", new_block]).strip('\n')
+    signed_block = subprocess.check_output(bc + ["combineblocksigs", new_block, '["' + blocksig + '"]'])
+    signed_block_json = json.loads(signed_block)
+    signed_block_hex = signed_block_json['hex']
+    subprocess.check_output(bc + ['submitblock', signed_block_hex])
+
+def generate_n_blocks(n,datadir):
+    """
+    Generates n blocks and places them into the given datadir
+    """
+    for i in range(0,n):
+        sign_block(datadir)
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--num')
+    parser.add_argument("--datadir")
+    num_blocks=100
+    args = vars(parser.parse_args())
+    datadir = args['datadir']
+    if args['num'] != None:
+        num_blocks=int(args['num'])
+    generate_n_blocks(num_blocks,datadir)