move src dir to cli and add it's own cmake file.

src/isatty.cpp

@@ -1,21 +0,0 @@
-#if _WIN32
-#include <io.h>
-#else
-#include <unistd.h>
-#define _isatty isatty
-#define _fileno fileno
-#endif
-#include "isatty.h"
-
-namespace eoskeygen {
-
-bool isatty(int fd) {
-    return ::_isatty(fd);
-}
-
-bool isatty(FILE* fd) {
-	// fileno() segfaults if fd is null.
-    return fd ? isatty(_fileno(fd)) : false;
-}
-
-} // namespace eoskeygen