checkbox structure changed
class for checking validity of password, yet to implement, done nothing
some signup methods updated
minor changes
just wrote author information
added author information, TODOs and parameter description also few method declarations
a table added for verification emails
minor change may be, can't remember
variables removed from global space

variables which were in global space, are now inside a class
added parameter PDO database connection
minor changes
added a persistent connection
minor changes
restructured code