[WIP] Exception refactoring

Fixes #90 
- [x] Create an `Exception` interface
- [x] Refactore existing exceptions and deprecate old ones
- [x] Create new exception to throw instead of the ones from STD or Symfony
- [ ] Update tests to use new exception class names (works without that because it's BC :v:)
- [ ] Update docblocks with the right version of deprecation
- [ ] Update docs
`PHP Fatal error:  Cannot use Gnugat\Redaktilo\Exception\DifferentLineBreaksFoundException as DifferentLineBreaksFoundException because the name is already in use in src/Gnugat/Redaktilo/Service/TextFactory.php on line 14` (line where the use statement is declared)

I really don't understand why this is happening because in `CommandInvoker`, we are in the same situation: there is a `use` statement with the default alias matching the class name of a class in the current namespace...