Abc and Yosys support reading from memory

[rikushoney]

ABC does not support reading/writing BLIF files from memory. This prevents us from skipping the filesystem and directly interfacing with ABC.

ABC's BLIF reading is implemented here (which corrosponds to the read_blif command).

It should be not too difficult to add a new function, e.g. Abc_FrameIoReadBlif, which reads BLIF from a file or string into the current framework instance. Abc_FrameIoWriteBlif should also be added to support writing the current network as BLIF to a file or buffer.

[rikushoney]

Yosys also does not support reading input from memory.

Currently, run_frontend is used to execute Yosys frontends such as read_verilog and read_blif -- which forces file I/O.