• Fix ccov-all-export on Windows platform with an if/else split.
• Add C support for clang-tidy, iwyu and cppcheck
• Mark detail C/C++ tool variables as advanced to not clutter normal output with implementation details
• Rework of tools.cmake items. The options of CLANG_TIDY, IWYU and CPPCHECK have been removed. Instead, it is up to the including project on when/how to enable these tools. The ability to 'reset' the tools, to disable them for certain scopes has been accommodated via the use of reset_* macros.

To remake the exact behaviour from before for tools.cmake, you can change something like this:

clang_tidy(...)
include_what_you_use(...)
cppcheck(...)

to

option(CLANG_TIDY "Turns on clang-tidy processing if it is found." OFF)
if(CLANG_TIDY)
  clang_tidy(...)
endif()

option(IWYU "Turns on include-what-you-use processing if it is found." OFF)
if(IWYU)
  include_what_you_use(...)
endif()

option(CPPCHECK "Turns on cppcheck processing if it is found." OFF)
if(CPPCHECK)
  cppcheck(...)
endif()