Built-in downloading with console display


This patch removes the original downloading method of calling an external tool and adds built-in support for downloads, along with a simple console display with a list of downloads.

To open the downloads list, press Ctrl+D. This list must be manually refreshed: simply press enter to do so. If you enter clean as a command, the list will be cleared. The shell command called to show the downloads is defined by the macro DLSTATUS in the config.def.h file.