NiftyDisplay: add "Suggestion" block

[kktsvetkov]

Add a new block (in the same fashion as "backtrace" and "source code") which will suggest how to fix the reported PHP error message. The idea is to help solve these issues easier without having to look elsewhere.

For example if there is a PHP notice "Array to string conversion", the suggestion will be something like:

You are probably trying to print or concatenate an array variable. You must check the type of the variable to understand whether it is a scalar or an array (or an object):
if (is_array($a)) {...

You can find more here:
stackoverflow.com/.../notice-array-to-string-conversion-in

In order to collect data for the suggestions, scan the PHP source code for zend_error(). Here is an example:

Zend/zend_list.c

0075 | if (ld->list_dtor_ex) {
0076 | ld->list_dtor_ex(&r);
0077 | }
0078 | } else {
0079 | zend_error(E_WARNING, "Unknown list entry type (%d)", r.type);

0116 | const char *space;
0117 | const char *class_name = get_active_class_name(&space);
0118 | zend_error(E_WARNING, "%s%s%s(): supplied resource is not a valid %s resource", class_name, space, get_active_function_name(), resource_type_name);

Put this in a separate class (\Wano\Display\Suggestions perhaps) and make it optional, enabled by default.