Changed Error Messages

Some error messages had to be adjusted to reflect the matching PHP type and to avoid confusion.

Calling the internal function mt_rand(), for instance with a parameter of the wrong type in PHP 5 lead to the following output:

php -r 'mt_rand("abc");'
PHP Warning:
mt_rand() expects parameter 1 to be long, string given

With PHP 7 the same error now shows the correct type information:

php -r 'mt_rand("abc");'
PHP Warning:
mt_rand() expects parameter 1 to be integer, string given