"Start to take this file to RAM now" button, menu option and config

[eerkatoka]

Especially when using external storage, it would be nice if it could be removed after few minutes, without copying files. At least 2 options to choose: VLC could take the whole file to RAM as is, or the file could be uncompressed while reading from storage, occupuying much more memory space but being lighter on processing when watched. This could start when user chooses so or VLC could start automatically after file is opened and possibly inform the user when the reading and/or decoding is done. VLC starts this only if there is enough free RAM+something like 200MB to spare. Option to use or not use swap.