Add /source-charset:utf-8 for MSVC++

CMakeLists.txt

@@ -326,7 +326,7 @@ IF(WIN32)
           # C4351: "new" behaviour, member array default initialization. Required since at least C++98, but funny MSVC throws a warning.
           # C4996: deprecated POSIX names (used in zlib)
 	  # C5105: defines in macros
-          SET(STEL_MSVC_FLAGS "/wd4244 /wd4305 /wd4351 /wd4996 /wd5105")
+          SET(STEL_MSVC_FLAGS "/wd4244 /wd4305 /wd4351 /wd4996 /wd5105 /source-charset:utf-8")
           # Avoid type conflict with C++17 standard
           # SET(STEL_MSVC_FLAGS "${STEL_MSVC_FLAGS} /D_HAS_STD_BYTE=0") # Don't do this in Qt6. Just avoid "using namespace std" anywhere! https://developercommunity.visualstudio.com/t/error-c2872-byte-ambiguous-symbol/93889
           # Set multiprocessing and minimal version of Windows