Introduce CompletionPolicy enum, use 'TextCompletion' for the new plain
text completion, and 'SemanticCompletion' or 'QuickFixCompletion' for
the existing cases.

Reviewed-by: Erik Verbruggen

Reviewed-by: hjk

Reviewed-by: Christian Kamm

Remove unneeded methods from API.

Makes them easy to use everywhere. Also when calling
QuickFixData::textOf and friends, it wasn't really clear which file
they would run on.

For answers to questions about where to insert a snippet/chunk of C++ code. Ok,
currently it will only find the One And Only place to insert method
declarations in classes, and it will need some tuning.

Revert "Revert "Try to fix the type rewriter.""

This reverts commit c9bc1e7c.

This reverts commit 33b19f02.

Reviewed-by: Roberto Raggi

We need to add the fully qualified name to the case statements.

Reviewed-by: Roberto Raggi

Done-with: Erik Verbruggen

Reviewed-by: Roberto Raggi

 * Use tr if a tr method is available at the object
 * Use QT_TRANSLATE_NOOP for global string constants
 * Do not offer to translate stuff inside QLatin1String and QLatin1Literal
 * Do not offer to wrap strings inside tr, trUtf8 and QT_TRANSLATE_NOOP
   with QLatin1String

 * Mark a string literal as translateable, using either
   tr() (if the object is perived from QObject) or
   QCoreApplacation::translate().