Merge remote-tracking branch 'ethereum/develop' into sol_contractCompiler

Conflicts:
	libsolidity/Types.cpp
NEG->BNOT change
Compiler for assignments.
Bugfix: Allow empty return statements without type checking.
Contract compiler and also add ExpressionStatement to AST.

ExpressionStatement functions as glue between Statements and Expressions.

This way it is possible to detect when the border between statements and
expressions is crossed while walking the AST. Note that ExpressionStatement is
not the only border, almost every statement can contains expressions.
Merge remote-tracking branch 'ethereum/develop' into sol_contractCompiler
Renamed file.
Function selector and variable (un)packing.
Actual contract creator and add solidity to AlethZero interface.
Merge remote-tracking branch 'ethereum/develop' into sol_contractCompiler

Conflicts:
	libsolidity/AST.cpp
	libsolidity/AST.h
	libsolidity/Compiler.cpp
	libsolidity/Compiler.h
	libsolidity/NameAndTypeResolver.h
	libsolidity/Types.cpp
	solc/main.cpp
	test/solidityCompiler.cpp
Bugfix: Swap before mod and div.
Some tests and bugfixes for the compiler.
Correct Solidity error formatting in AlethZero.
Merge remote-tracking branch 'ethereum/develop' into sol_contractCompiler

Conflicts:
	alethzero/CMakeLists.txt
Test adjustments.
Stylistic changes.
Fixed doxygen comment.
Added doxygen comment.
Converted all asserts to exceptions.
Stylistic corrections.