enable parallel check of languages

Use parallel to spawn as many subprocesses as possible to accelerate
the tests.
Change Maruku check to fully functional mode

this is cleans up the code.
Force output of Rake messages to stderr
Monospace branch names
Monospace branch names
Note that, when locally copying, the hardlinked files are the objects

Previously it was possible to infer from this sentence that the actual
work tree was hard linked, but it is the Git objects that are
hard linked. This makes the passage much less ambiguous.
Merge pull request #604 from cdown/master

Note that, when locally copying, the hardlinked files are the objects
[de] First translation of chapter 6.6 (submodules)
Merge pull request #605 from progit-de/next

[de] First translation of chapter 6.6 (submodules)
[fr] update README to bypass progit-fr

Now the french translation's fixup don't need a specific repo. Just
use the main repo for forking and submitting.
[de] First translation of chapter 6.7 (subtree-merge)
[de] First translation of chapter 6.8 (summary)
[de] Use Dir instead of dir and Du instead of Du
Reviewing translation

to ensure compliance within the chapter, before proceeding translation
Reviewing translation
Reviewing translation
Reviewing translation
Reviewed "Una breve nota su SHA-1"
Reviewing translation
Fixed typo