Merge pull request #104 from vipjeffreylee/develop

fixed Ubuntu12.04 compile error
Stack/argument awareness in LLL.
Call and multi in LLL.
Merge branch 'develop' of github.com:ethereum/cpp-ethereum into develop

Conflicts:
	libethereum/Instruction.h
Remove clang bug workarounds fixed with latest XCode tools release.
Fix DSO missing from command line by adding lpthread to linker
Merge pull request #111 from danielhams/dhdevelop

Remove clang bug workarounds fixed with latest XCode 5.1 tools release.
use CMAKE_THREAD_LIBS_INIT for unix environment so you can pass pthread library if needed
Merge pull request #113 from tymat/pthread

CMAKE_THREAD_LIBS for UNIX platform
Added help command in interactive mode
Merge pull request #114 from msimovic/interactivehelpupdate

Added help command in interactive mode
No libsnappy - it breaks my build.
Merge branch 'develop' of github.com:ethereum/cpp-ethereum into develop

Conflicts:
	libethereum/CMakeLists.txt