login system (finish)

Include logout button and check incorrect to login
#file function.php is file for reuse code
Revert "login system (finish)"

This reverts commit 56f372b3cedcdb8d2079bda6650d78197a6c6f92.
log system (finish) **again

Include logout and check incorrect username and password to system
#file function.php is file for reuse code
Merge remote-tracking branch 'origin/master'

Conflicts:
	index.php