This preserves the current behavior of using a string value as Solidity
source code, but now also supports instances of the `file` type, and
will use the `name` property of the file object to pass to the
subprocess invocation of solc.
This implementation also now ensures resource cleanup for the stdout and
stderr pipe handles.
Make use of compiling via file handles in multi_tx_analysis
This will enable import statements in Solidity code to work for the
Manticore CLI out of the box
Note, Manticore still wants the source code, so if we compiled using a file
handle, rather than a source string, we need to read in the source
fixes#705
4a98110f4a