Static validation and problem markers for Flux files (closes #20)

Reports different problem types in editor and problems view:

- Errors for missing commands (not declared in flux.properties)
- Errors for successive commands with incompatible input or output
- Warnings for commands with missing `@In` annotation, infos for `@Out`

![metafacture-ide-problem-markers](https://f.cloud.github.com/assets/128229/642320/1b71e502-d356-11e2-9961-7024746f6a79.png)

Deployed for testing (run 'Check for updates' or install from Marketplace).

@acka47 could you give it a try and +1 it here if it works for you.