Replaced special chars with HTML code
Added two new methods

Added methods escape_string and server_info.
Removed old MYSQL_ASSOC parameter

Removed old parameter MYSQL_ASSOC from queryrow method. The new
MYSQLI_ASSOC is the default, also we should consider to use
mysqli_fetch_assoc instead of mysqli_fetch_array, since the only value
used is _ASSOC.
Replace old function with new method

Replaced deprecated mysql_real_escape_string function with new
escape_string method that uses mysqli_real_escape_string
Fixed code even if commented
Replaced old function with new method

Replaced old mysql_get_server_info with server_info method that uses
mysqli_get_server_info