Initial Simplermenu+ issues

[acmeplus]

This is a first issue to keep track of all the things are still missing

• Joystick support is missing, reuse the implementation that is in the simplemenu_cpp repo
• Some coordinates are still hardcoded and need to be read from config.ini or theme.ini
• There's only support for config.ini, nothing for theme.ini yet
• System Menu is completely missing
• RomMenu is present (press m) but does not have any function yet
• There's no exit/quit key yet
• There's no support for section_groups/*.ini files (consoles.ini, arcades.ini, etc.)
• There's no support for section groups (organize several systems under a category)
• Need to add support to ignore Mac .DS_Store, and ._* files
• Code refactoring: rethink class structure, menu driven or event driven
• Finish settings management using an enum class via Configuration.cpp
• Merge both experimental branches (settings management + menu management).
• Save settings to file
• Add Control class to manage the mapping between keys and menu actions (left, right, up, down, a, b, start...)
• Add auto theme scaling (for resolutions higher/lower than default 640x480)
• Save application state (returning to menu from a rom should return to the rom listing, same for returning from a menu to the previous selection.