Updates formatter_bytecode.py to support compilation and disassembly for
synthetic formatters, in other words support for multiple functions
(signatures).
This includes a number of other changes:
* String parsing and encoding have bugs fixed
* CLI args are updated, primarily to support an output file
* Added uleb encoding/decoding support
This work is a prelude the ongoing work of a Python to formatter
bytecode compiler. The python compiler to emit assembly, and this module
(formatter_bytecode) will compile it into binary bytecode.