Reduces the number of files that need to be recompiled
when making changes to FileUtil.h.

The MemoryWindow.cpp strings should be the same as the
MemoryCheckDlg.cpp strings so that translators don't
have to translate very similar strings twice.

Also adding i18n comments. These strings are *very* easy
to misinterpret in my opinion.

Event tables are the old method of performing event binding.

Keeps specific UI element initialization separate from one another.

std::string's operator+ will handle this. Also move std::string to where
they're actually needed. There's no need to construct an unnecessary
string if the first failure case occurs.