RenderersSettings: Turn off VSync by default.

VSync has issues playing some files and has limited effect in a typical usage scenario.

Fixes #2947.
External filters page: Show the path of the filter using tooltips.
DVBChannel: Remove an unused function.

This function doesn't really have any good reason to exist.
Updated Korean translation

Refs: #1526
Cosmetic: Fix a typo.
Some testing on SetAlwaysOnTop. (not working)
PPageExternalFilters: cosmetics.

* Use more meaningful functions names.
* Use correct visibility for the members variables and functions.