[session] use instance config, not global config, to determine session auto_start

[session] do not auto start the session if auto_start is set to false

[migrate] improved migration enumeration; migrate packages before modules

[profiler] don't attempt to get session data if no session is active

[session] add static method to check if a given session is active or not

[session] add driver method to return its internal state

[package] added installed() method

[module] added installed() method

[profiler] do not try to access Session data if no session is active

add DBUtil::database_exists()

[arr] add option to multisort to prevent re-indexing of indexed arrays

[arr] update is_assoc() to test for non-consequtive numeric keys; fixed multisort should not re-index array

fixed typo

Str::random() replaced mt_rand() by random_int(), which is more reliable and random

[migrate] add has() method