qt: Remove '0 BTC' placeholder from translation
fix compilation error in core_io.h

- error: 'vector' in namespace 'std' does not name a type
- add <vector> include in core_io.h
- remove <vector> includes from core_read.cpp and core_write.cpp
add license header to core_io.h, core_read/_write.cpp
Merge branch 'merge-rawtx2' into merge-rawtx3
Declare SignatureHash() in script.h
Merge branch 'whyextern' of git://github.com/jtimon/bitcoin into merge-whyextern