0.2.3
fix release version and Makefile.am substitutions; 0.2.1 release
[module] rework module code to its own file with cleanup and docs
Add native CLOSE_FD support where available
add extern "C" to headers
[core] add verto_get_fd_state() and verto_set_fd_state(); enable backends to report fd state
[all] unset all emulatable 'actual' flags by default; allows for easer forward compatibility
[core] don't write to recently free'd memory
Add autoclose feature for file descriptor events