Optimized Amiga emulator for the Raspberry Pi and other Linux devices

🐛 Bugfixes

DiskSwapper slots should be 10
Virtual Keyboard options were not saved correctly
fixed several memory leaks from the GUI
don't shutdown graphics when showing GUI message
Fixed memory leak when using AROS rom
fixed crash on startup on x86_64 platform
fix naming of start_minimized option
rename local variable to avoid shadow of global one
fixed crash if Restart was pressed
GUI would not redraw always after ShowMessage or ShowHelp was triggered (fixes #1148)

🔨 Improvements

added flatpak package files (x86_64 only, for now)
improved help text in DiskSwapper panel
attempt to transliterate characters that fail to be converted (#1124)
don't disable CD drive if no image path is specified (#1129)
if start_minimized is specified, do not show a window on startup
check for usage help cmd line parameter early
Hide the Linux hidden directories from dialogs (#1147)
improved help text in GUI->Expansions (fixes #1150)
added VSync option (fixes #1149)
added missing help text in GUI->Priority

🏗️ Build System

added RPI4 debian builds
replace self-hosted RPI builds with docker
Added RPI5 in automated builds
updated flatpak metainfo
updated Github workflow, include flatpak in releases
add libserialport sources to externals
added USE_LTO option in Makefile
fixed cmake build (for x86-64) on master branch

Platforms

add Raspberry Pi5 (#1136 by cmitu)
add experimental RISC-V 64-bit (no JIT) (#1127)