Begin work on standalone version

Now the plugin ZIP file (DeDRM_plugin.zip) can be run with a normal
Python interpreter as if it were a Python file (try
`python3 DeDRM_plugin.zip --help`). This way I can begin building a
standalone version (that can run without Calibre) without having to
duplicate a ton of code.

DeDRM_plugin/zipfix.py

@@ -20,14 +20,13 @@ Re-write zip (or ePub) fixing problems with file names (and mimetype entry).
 __license__ = 'GPL v3'
 __version__ = "1.1"
 
-import sys
+import sys, os
+
+# Calibre stuff - so we can import from our ZIP without absolute module name
+sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+
 import zlib
-try:
-    import zipfilerugged
-except:
-    import calibre_plugins.dedrm.zipfilerugged as zipfilerugged
-import os
-import os.path
+import zipfilerugged
 import getopt
 from struct import unpack