CMake: check if std::regex present, and define a corresponding macro
StringUtils: use the HAVE_STDREGEX define instead of version checks
CMake: provide a basic facility for #define-based settings
CMake: provide a basic facility for #define-based settings

Conflicts:
	dev/CMakeLists.txt
CMake: store HAVE_STDREGEX in config.h to include it elsewhere
StringUtils: use HAVE_STDREGEX supplied by CMake
JPLEph: replace a weird statement/typo that was causing build failure on Windows
Merge branch 'fix/jpleph-build-failure'
Merge branch 'feature/cmake-configuration-file'
Merge branch 'fix/regex-capability-check'

Conflicts:
	dev/CMakeLists.txt