Significant changes to on save syntax checking

• Allow spaces in filenames
• Crates with multiple targets are automatically detected.
• Highlight/outline the regions where the message is.
• Include a link for Exxxx errors to a web page.
• Include a way to close/hide messages.
• Support non-ascii output on certain platforms.
• Display more messages (notes, macro expansions, etc.)
• If there is a message for a file not currently open, print it to the console
• Add Rust symbols to global index