replace urlgrabber to enable python3 compatibility

- new module grabber.py
  * OscMirrorGroup to keep urlgrabber.mirrorgroup behavior
  * OscFileGrabber moved here

- meter.py
  * reworked to use progressbar module instead of progressbar
    of urlgrabber and simplified the module.

- babysitter.py
  * removed URLGrabErrorr

- build.py
  * removed adding of url_local to urllist. (not needed anymore)
  * removed URLGrabError

- commandline.py
  * switched from urlgrabber.urlgrab to OscFileGrabber().urlgrab

- core.py
  * reworked progressbar behavior

- fetch.py
  * removed join_url (not needed anymore)
  * moved OscFileGrabber to grabber.py
  * removed failureReport (not needed anymore)

osc/core.py

@@ -5992,8 +5992,11 @@ def streamfile(url, http_meth = http_GET, bufsize=8192, data=None, progress_obj=
         cl = int(cl)
 
     if progress_obj:
-        basename = os.path.basename(urlsplit(url)[2])
-        progress_obj.start(basename=basename, text=text, size=cl)
+        if not text:
+            basename = os.path.basename(urlsplit(url)[2])
+        else:
+            basename = text
+        progress_obj.start(basename, cl)
 
     if bufsize == "line":
         bufsize = 8192
@@ -6012,7 +6015,7 @@ def streamfile(url, http_meth = http_GET, bufsize=8192, data=None, progress_obj=
         yield data
 
     if progress_obj:
-        progress_obj.end(read)
+        progress_obj.end()
     f.close()
 
     if not cl is None and read != cl: