[TASK] files.php: one tempfile per URL
[TASK] files.php: one tempfile per URL

Having one temporary file per URL allows easier debugging.

Two current examples:

- develop: `.magerun-phar.~dl-temp-77e90c965add1adbdfc3bdc3d343f75b`
- master:  `.magerun-phar.~dl-temp-ed719d117fffd4e2da99160eaa9cf90b`

Just a quick addition.

EmPeWe/n98-magerun,pocallaghan/n98-magerun,EmPeWe/n98-magerun,pocallaghan/n98-magerun,tkn98/n98-magerun,pocallaghan/n98-magerun,EmPeWe/n98-magerun,therouv/n98-magerun,tkn98/n98-magerun,tkn98/n98-magerun,therouv/n98-magerun