C++ code indentation and formatting based on LibFormat

LibFormat is a library which is used by clang-format and contains most of its functionality.

Since our built-in code indentation/formatting lacks the support for modern C++ it can be a good idea to use formatting provided by clang.

Advantages:

• better modern C++ support
• more formatting settings than currently
• many projects already have configuration file for it (.clang-format)

Problems found so far:

• clang-format does not expect unfinished statements
• tricking clang-format to indent unfinished statements is quite complicated and is not reliable
• ideally requires some upstream changes to avoid tricks from QtC side