VIM: flags for setting options

#define OPT_FREE        1       // free old value if it was allocated
#define OPT_GLOBAL      2       // use global value
#define OPT_LOCAL       4       // use local value
#define OPT_MODELINE    8       // option in modeline. Needed because some options can not be set from a mode line.
#define OPT_WINONLY     16      // only set window-local options
#define OPT_NOWIN       32      // don't set window-local options