Merge pull request #8 from lualatex/master

sync with lualatex repo
It can be normal for a function to return false
In simple callbacks, we stop on a false return

(so that we can truely disable hyphenation)
Adding a test
Bumping date and refreshing callback list
updating NEWS file
Logging is just spoiling logs when done with hyphenate callback...
Merge pull request #16 from eroux/master

Minor improvements in mcb, going 0.7