Added a translation:debug command
[FrameworkBundle] fixed edge cases for translation:debug and tweaked the output
feature #10368 [FrameworkBundle] Added a translation:debug command (fabpot)

This PR was merged into the 2.5-dev branch.

Discussion
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[FrameworkBundle] Added a translation:debug command

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

This PR is based on #10076 but fixes a bunch of issues for edge cases. It also uses the new Table helper.

Original description:

This pull request adds a `translation:debug` command that can be used to inspect unused / missing messages and compare them with the fallback ones (for example to detect copy pasted strings). This is inspired by this ruby project https://github.com/glebm/i18n-tasks

Example of output:

![image](https://f.cloud.github.com/assets/47313/2311673/84ae301c-a2f3-11e3-8bf6-96034369e46c.png)

Commits
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f039bde [FrameworkBundle] fixed edge cases for translation:debug and tweaked the output
597a310 Added a translation:debug command