Update norwegian.lua for CTH v0.4

Added the five missing translations after CTH v0.4 beta 2.
Merge pull request #349 from Grimdoc/patch-1

Update norwegian.lua for CTH v0.4
Fixed hell deaths bug #351

In die.lua:die_tick_reaper:tryHellDeathSpawnScenario() I had not
included responses to the possibility of this function's
findIdleTile() calls returning nil tile coordinates, so in this
commit I've simply added two IF statement conditions to check
that there are no nil tile coordinates before they are used.
Merge pull request #353 from J-Shep/351_fix

Fixed hell deaths error #351
Contributing.txt: what are your working on?

I think this file should make sure that new contributors don't make the mistake of not telling other devs what they are working on and consequently wasting their free time/ another developer's free time by working on the same issue.

I've also added "git diff --check" to the "Review your changes" instructions.
Merge pull request #366 from J-Shep/contributingsay_what_your_working_on

Contributing.txt: what are you working on?
Fix 'Warning: Proper idle not in action_queue'

The queue action's action_queue_find_idle() function would wrongly announce an error when it could not find an idle action in its user's action queue because they were using a drinks machine with a use_object action. This commit makes this function announce a warning instead.
Merge pull request #367 from phillipp/proper-idle-action-fix

@phillipp thanks for making the changes I requested, I will merge this pull request now.