Added a drop-in extension

If you would like the built-in ini_ functions to not be broken but also would prefer to not manually edit your code (for example, if you are using an extension which uses INI functions but breaks because of built-in's limitations), here's a thing:

If you import the attached file_ini_instead_of_ini extension, it will replace the built-in functions with scripts that call file_ini's functions, so doing ini_open would call file_ini_open and store the file in a global variable. Then the other ini_* functions would call file_ini_* functions on this file.

This way no additional work is required.