Make test output for upstream remote conditional

If someone doesn't have a remote tracking wbsoft/frescobaldi.git
one can't test for it.
Fix color in 'git branch' command

As Janek reported colored git output (user setting)
shows up as color codes in the GUI.
disabling coloring for the current command does fix it.
Fix upstream lookup

When looking for the remote that is tracking the official repo
I relied on 'wbsoft/frescobaldi.git' to be present.
Obviously 'wbsoft/frescobaldi' is enough.
Merge pull request #228 from uliska/fix-color-codes

Fix color in 'git branch' command
Merge pull request #227 from uliska/fix-test

Fix lookup of 'upstream' remote
no need to import vcs.menu when we are not using it
no need to bootstrap vcs in main, it is imported for the first time in mainwindow which is early enough
Update German translation (Preview-mode)

Translate new Preview-mode documentation.
Look through 'fuzzy' entries.
Add note about default session to Help
Merge pull request #229 from uliska/de-translate-preview

Update German translation (Preview-mode)
Merge pull request #230 from uliska/session-doc

Add note about default session to Help
space in l10n string
pot/po/nl
correct subtle bug
smarter
growing text widget
open search/replace help when f1 pressed in search widget
use wordboundary stuff when picking search word

also escape it when regex is turned on
dont keep replaced positions
improve tab and backtab behaviour of search widget