This was needed to make the splash screen appear, and was missed when
the splash screen was killed.

Aegisub needs Lua built as C++ (for stack unwinding on errors). No one
packages it like that, so at the moment we can't actually use systme
packages for Lua.

Fixes a bunch of memory leaks on Automation errors.

It has zero benefit and forces an extra copy.

Apparently flushing immediately after setting the clipboard sometimes
doesn't work.

Passing a codepage makes libass convert to UTF-8 even if it's already
UTF-8.