Add sysconfig platform

[gillg]

Add sysconfig platform to let user create custom scripts with certain extension in a specified "rom" directory.

Please make sure your PR is ready to be merged !

• You added the changes in CHANGELOG.md
• You choose the right repository branch to make the PR
• You described the PR as below

Changes :

• Add a new platform ID called "sysconfig"
• This kind of system is igned from scrapper, and title is "Configuration" instead of "X Games available"
• This kind of system has no "advanced game options"
• User can create a script wraper or exectute script directly, choose wich extentions to use in a specific dir, add icons with his gamelist.xml, etc.

[substring]

Hi !
Although the idea is quite interesting, it's also a massive security hole to run .sh files with bash this way when files are not u+x chmodded. I know that may sound too precautious, but there is a big risk here.

What's your idea behind ? Run "anything" (I'm thinking about standalone games or such, but you may have some other ideas in mind).

I'm holding my approval for now.

[gillg]

Hi ! I'm according with you about a potential security risk, but it's a fake argument. Actually anyone can do this, you have just to change <command> in any system of your es_system.cfg and change extension to .sh for example... by this way anywone could already put /usr/bin/ as rom path for example and "bash %ROM%" as command.

So, my wich is just to clarify this process, by adding a special platform, not handled as game platform. After you could lauch some custom bash/python/php/other scripts, for example to auto download and install themes, launch a coffee by network, ask for a pizza.... so all you could imagine and code in your favorite language :)

[substring]

Our es_systems.cfg is in a RO fs that requires login ;) so it's not that trivial to edit it.

Concerning themes download etc ... It's better to have it done in a "recalbox way". But i do understand the meaning of this PR. @digitalLumberjack and @rockaddicted also have their word to say :)

[gillg]

Plop :)

[substring]

hey @gillg

Few things:

• we moved this repo to https://gitlab.com/recalbox/recalbox-emulationstation, so the github one is now mere obsolete
• i'm not sure we want to include some "system" system. The last time I talked about such a feature with other members of the team, they preferred keeping ES as a roms frontend, except what can be done in menus