Feature Details

Add a textbox in Emulator settings tab, similar to launch arguments textbox, called "ROM filters"
User type filters in string format .{extension1} [, {.extension2}, {.extension3}...] example: .zip, .iso. If leave empty, treat it like .*
When user use feature Scan for Added ROMs, apply all filters from all platforms/emulators
When user scan for specific platform, apply all filters from that platform
When user scan for mixed games, apply filters from all emulators related to those game.

Example

User defined 2 platform, 4 emulators and 2 games for each emulators

[Platform / emulator, filter, games]

PS2 / PCSX2, filter: ".iso", games: ps2G1, ps2G2

PS2 / PCSX3, filter: ".zip", games: ps2G3, ps2G4

Wii / Dolphin, filter: ".wii", games: wiiG1, wiiG2

Wii / Donkey, filter: ".woo", games: wiiG3, wiiG4

When user use Scan for Added ROMs, search all *.iso, *.zip, *.wii, *.woo files for importing.
When user use Scan for PS2, search all *.iso, *.zip files for importing.
When user selected wiiG3 and ps2G2 for scan, search all *.woo, *.iso files for importing.