This change permits to use up-to-date compilers, clang-tidy and
clang-format
It also refactor the tidy/format step to drop the binary selection from
scripts and perform it directly in travis
* Move GCC to GCC 6 & GCC 7
* Move Clang to Clang 3.6 & Clang 4.0
* LINT moves from Clang 3.9 to Clang 4.0
* Move XCode 7.3 to 8.0
* Use more travis tricks to install compilers instead of adding complexity to our build script
* Clang format fixes on checked files (compat Cpp11 instead of Cpp03)
* Mingw GCC update from 4.8.4 to 5.3 (Ubuntu Xenial)
* Drop mingw cmake generated files and add them to gitignore
* Proper support for continuation indents in clang format
* make src/wieldmesh.h proper and remove it from whitelist
* Add CLion default build directories in .gitignore
* [BUILD] Add clang format + build skipping
* Add clang-format tool to check codestyle.
Warning: it check the whole modified file, not the diff part, it's why it's lazy. Please also look if rules are perfect, i take the Linux codestyle from LLVM site
Fix issue #5415
* Skip building project if no file is modified
* Fix a wrong brace to trigger LINT
* Make lint step outside of unix build scope
* Add AccessModifierOffset: -8
* Typo fix & needs compile fix
* Fix header priorities
