[Qt-creator] Name validation in rename symbol

[Volodymyr Zibarov]

The new feature in Qt Creator 10 is name validation during renaming a 
symbol.

The old behavior without the validation made possible to make 
refactoring tricks, like move variable into a struct, or replace public 
member usage with a get method. For example:

name -> myStruct.name

name -> getName()

Let's add an option to disable name validation

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Volodymyr Zibarov