v0.8.0

• Bug fixes in argument handling.
• Do not require fn main() in script files - surround the script file with fn main() { .. } if no line starts with fn main().
• Add -o/--cargo-output option to see output from Cargo also in successful builds.
• Define the RUST_SCRIPT_* environment variables also at compilation time - not only at runtime as before.
  • This enables using include!, include_str! and similar from scripts - see #6.