Support multiple assignment in inline assembly

[chriseth]

Fixes #2923.

[axic]

Added changelog and fixed travis.

[chriseth]

Wonderful, thanks!

[axic]

Added tests for the parser errors and managed to crash:

unknown location:0: fatal error: in "JuliaParser/recursion_depth": memory access violation at address: 0x7fff54b11f50: invalid permissions
/Users/alex/Projects/solidity/test/libjulia/Parser.cpp:240: last checkpoint: "recursion_depth" entry.

[chriseth]

This probably means we incorrectly estimated the stack frame size on one of the architectures.

[axic]

It seems like going to a vector was enough to tip it over:

 -			assignment.variableName = identifier;
 +			assignment.variableNames.emplace_back(identifier);

[axic]

Added more tests and fixed the stack limit for Mac.

[chriseth]

Good to merge!

[axic]

This crashes on travis:

/home/travis/build/ethereum/solidity/libsolidity/codegen/ContractCompiler.cpp(562): fatal error in "auto dev::solidity::ContractCompiler::visit(const dev::solidity::InlineAssembly &)::(anonymous class)::operator()(const assembly::Identifier &, julia::IdentifierContext, julia::AbstractAssembly &) const": std::exception: 
/home/travis/build/ethereum/solidity/test/RPCSession.cpp(324): last checkpoint

[axic]

This code is triggering it:

               contract C {
                        function f() pure returns (bytes32 ret) {
                                assembly {
                                        ret := keccak256(0, 0)
                                }
                        }
                        function g() pure returns (bytes32 ret) {
                                assembly {
                                        0
                                        0
                                        keccak256
                                        =: ret
                                }
                        }
                        function h() pure returns (bytes32 ret) {
                                assembly {
                                        ret := sha3(0, 0)
                                }
                        }
                        function i() pure returns (bytes32 ret) {
                                assembly {
                                        0
                                        0
                                        sha3
                                        =: ret
                                }
                        }
                }

Out of this, the stack assignment (=: ret) parts fail.

[chriseth]

Ok, should be working now.

[axic]

@chriseth please merge if tests pass