Re-created PNG files using updated script to address 'white' transparent pixel issue discussed at #347. Added or modified icons for the folllowing systems/cores: - Atari - VCS - BBC - Bridge Companion - Epoch - Cassette Vision Jr - Gakken - Compact Vision TV Boy - Intellivision - Amico - Interton - Video 2000 - Microsoft - XBOX Series X - Nichibutsu - My Vision - Pioneer - LaserActive - Quake - Quake2 - Quake3 - Sega - Beena - Tiger - Game.com Pocket Pro - Tomy - Tutor - Unisonic - Champion 2711 - VM Labs - Nuon - VTech - 3D Gamate
Added input and menu icons to align with the reference monochrome theme and address Issue #262 for the Automatic and Systematic themes. Refined some existing menu icons for consistency in design. Optimized PNGs with ImageOptim.
