Fix hscope terminating when a file using CPP uses #error.

This was because cpphs calls error if it encounteres #error.

We now catch this exception.
Add TODO about use of head
Add verbose mode
Prevent endless loop in extensions
cabal: Depend on uniplate-1.6.11 to fix performance regression.

See http://neilmitchell.blogspot.jp/2013/08/destroying-performance-with-strictness.html
Merge pull request #6 from nh2/nh2fixes

Some fixes