Move Compiler - set stdlib root

[ghost]

discussion is here
PR is here

The idea is add --stdlib-root ~/repos/bcx/libra/language/stdlib/ argument to set stdlib root path, that the Move compiler can find Move stdlib.

Improvement:
Use -I to set library path such as GCC/Clang:

./compiler -I ~/repos/bcx/libra/language/stdlib/ -I ~/repos/bcx/libra/language/others_lib ~/hello.mvir

[liangping]

@yinjimmy Do you mind integrate with Move Runner.

Move Runner is a tool focused on project management, including compile, build and run.

let's work together.

[ghost]

The new version compiler use --deps to support this feature. But has some issues:

1. compile error
   A: solve with --no-stdlib

$ ./target/debug/compiler ~/hello.mvir --address 0x1
thread 'main' panicked at 'Failed to compile script: Duplicate dependency module for 00000000000000000000000000000001.Signer', language/compiler/src/main.rs:144:14
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

2. no output file, output file is in the same folder of ~/hello.mvir -> ~/hello.mv

$ ./target/debug/compiler ~/hello.mvir   --address 0x2 --no-stdlib
$ ls ~/hello.mv*
/Users/admin/hello.mv    # output file
/Users/admin/hello.mvir