Added possibility to run XML conversion from shell

Signed-off-by: Grzegorz Latosinski <glatosinski@antmicro.com>

vtr_xml_utils/__main__.py

diff --git a/vtr_xml_utils/__main__.py b/vtr_xml_utils/__main__.py
new file mode 100644
index 0000000..7204119
--- /dev/null
+++ b/vtr_xml_utils/__main__.py
@@ -0,0 +1,46 @@
+#!/usr/bin/env python3
+
+from . import convert
+
+import argparse
+import sys
+import os
+
+
+def main(args):
+    if not os.path.isfile(args.input_xml):
+        print("The {} file does not exist or is a directory"
+              .format(args.input_xml))
+        exit(2)
+    elif not os.path.isdir(os.path.dirname(os.path.realpath(args.output))):
+        print("The {} file cannot be created - no such directory"
+              .format(args.output))
+        exit(2)
+    result = convert.vtr_stylize_xml(args.input_xml)
+    with open(args.output, 'w') as out:
+        out.write(result)
+    exit(0)
+
+
+if __name__ == '__main__':
+    parser = argparse.ArgumentParser(
+        prog='vtr_xml_utils',
+        description="A tool for applying styling changes to the XML files \
+                     for Verilog"
+    )
+    parser.add_argument(
+        "input_xml",
+        metavar="input.xml",
+        type=str,
+        help="The path to file that needs to be stylized with XSL files",
+    )
+    parser.add_argument(
+        "--output",
+        "-o",
+        type=str,
+        default="output.xml",
+        help="Output filename default 'output.xml'"
+    )
+
+    args = parser.parse_args()
+    sys.exit(main(args))