#132 Add Clang-Format and Clang-Tidy checks

[vityaman]

• Added .clang-format config file
• Added .clang-tidy config file
• Formatted code to satisfy format checks
• Edited code to satisfy lint checks
• Running clang-tidy only on source directory (not tests), because it works very slowly
• Fixed ccache key

If you have serious concerns about clang-tidy fixes or is it difficult to read the code, I can close this MR and then open one with only Clang-Format changes and then another one with only Clang-Tidy changes.

[mike-lischke]

I have no objections, except the short line length. A length of 80 characters is IMO too small these days. Better is 100 or 120, but as always with formatting, this is a personal preference. Good to see tab indentation has been replaced with space indentation.

[vityaman]

• Raised line width up to 100
• Changed formatting rules a little
• Did tiny-tiny test refactoring

[mike-lischke]

Thanks!