Issue 233

This PR includes a lot of changes.

- Refactoring scxml-analyzer.js (Will probably cause merge conflicts)
  - Shorter error code
  - Async node traversing
  - Commits all changes at the end, after traversing all nodes.
- File inlining
  - New file "file-utils.js" somewhat similar to "inline-srcs.js"
  - If there is a running async process for file inlining, defers committing changes and waits for all async processes to end.
  - Removed "inline-srcs.js"