stripslashes_utf8 is only declared when not exist
AccessControl now checks before decoding

The entries of NAV files are decoded as json only if they are string
Alternative way to disable access
Moved functionality to String_Utility

String_Utility is now responsible of escaping and unescaping strings and
characters
Also moved json_decode_array to String_Utility
utf8_str_split only declared when not exist
extended escape functionality
database is no longer treated as plug-in
session is no longer treated as plug-in