Remove prefixing from SM.ml, change bytecode format.

[ancavar]

As part of the ongoing virtual machine implementation, it was decided to:

• separate function and global prefixing from the stack machine part and move it to the compilation part only
• change bytecode format (add a flag for public symbols, remove opcode for write, read etc.)

Note: previously, init functions for modules were prefixed with init, but with the current implementation we have a collision with, for instance, initMatcher in the Matcher module (since we no longer prefix user functions with L). The proposed change is to prefix init functions with Init instead.

Aditional discussion ancavar#4

[ProgMiner]

remove opcode for write, read etc.

Note, actually these opcodes wasn't removed since they are needed as long as we have no a working full-fledged VM.