Composer-Setup 6.3.0

• Added existing version uninstallation. This is done silently in the background just before the main installation and creates an Uninstall Log in the temp directory.
• Removed approval page for ini updates, which now happen automatically and are shown to the user on the Ready to Install page.
• Reworked ini update handling to fix extension_dir errors.
• Improved PHP checks and changed to using runphp for all scripts.
• Added output capturing from runphp using cmd.exe.
• Changed runphp to execute any commands, rather than just -v, with a 30 second safety timeout.