Add baseurl option to make_repo and actually set package urls

Also actually use said URL when calling 'install' operator

make_repo.py

@@ -163,7 +163,7 @@ class Repository:
         log.info("repo.json written to %s" % path)
 
 
-def make_repo(path: Path, name: str) -> Repository:
+def make_repo(path: Path, name: str, baseurl: str) -> Repository:
     """Make repo.json for files in directory 'path'"""
 
     repo = Repository(name)
@@ -181,6 +181,7 @@ def make_repo(path: Path, name: str) -> Repository:
                     )
 
         package = Package(addon, bl_info)
+        package.url = baseurl + package.path.name
         repo.add_package(package)
 
     log.info("Repository generation successful")
@@ -194,6 +195,9 @@ def main():
             help="Increase verbosity (can be used multiple times)",
             action="count",
             default=0)
+    parser.add_argument('-u', '--baseurl',
+            #TODO: support relative URLs
+            help="Component of URL leading up to the package filename.")
     parser.add_argument('-n', '--name',
             help="Name of repo (defaults to basename of 'path')")
     parser.add_argument('-o', '--output',
@@ -212,9 +216,12 @@ def main():
     if args.name is None:
         args.name = args.path.name
 
+    if args.baseurl is None:
+        log.warning("No baseurl given, package URLs will just be filenames")
+        args.baseurl = ""
     log.debug("Repository name: '%s'" % args.name)
 
-    repo = make_repo(args.path, args.name)
+    repo = make_repo(args.path, args.name, args.baseurl)
     repo.dump(args.output)
 
 if __name__ == '__main__':