-u option ignored

[Karl-Philipp Richter]

invoking `transcode` with option `-u 10,10` doesn't cause any parallelization in the form of usage of multiple threads. Either the option is ignored or it isn't possible to parallelize in which case this information desperately need to be added to the manpage (to the section of the `-u` option in order to be not confusing.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: transcode 3:1.1.7-9build3
Uname: Linux 4.0.1-040001-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.1
Architecture: amd64
CurrentDesktop: Unity
Date: Sat May 23 22:05:22 2015
EcryptfsInUse: Yes
InstallationDate: Installed on 2015-04-02 (50 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Beta amd64 (20150326)
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: transcode
SystemImageInfo:
 current build number: 0
 device name:
 channel: daily
 last update: Unknown
UpgradeStatus: No upgrade log present (probably fresh install)