Add an interface for channel list and change to the web server.

This change adds a JSON interface for obtaining the list of channels
currently available via the DVB interface in MPC-HC, and a simple facility
which allows the client to change the currently played channel.
CAppSettings: Remove the copy constructor and assignment operator.

We don't want to accidentally copy the settings.

Also don't mark the constructor as virtual.
Don't warn the user when some DVD hooks fail.

Those hooks aren't critical for DVD playback and they often fail due to an incompatibility with NVIDIA drivers on some systems which unfortunately we can't fix on our side.

Refs: #3739.
VSFilter: Be more careful when using IMediaSample2 interface.
Sync Renderer: Remove some unneeded casts.
Update translations from Transifex:

 - Basque
 - Catalan
 - Chinese (simplified and traditional)
 - French
 - German
 - Greek
 - Hungarian
 - Japanese
 - Polish
 - Slovak
 - Turkish
 - Ukrainian
Add an option to prevent creating the external style file when saving a subtitle.
Updated LAV Filters to 0.61.2-40-42f583f (custom build based on 0.61.2-35-6c73517)

Important change:
 - LAV Video: Fix some issues with DVD subtitles (flashing, overlapping and generally all kind of timing issues) (fixes #4032).
Cosmetic changes.

* use `nullptr` instead of `0` when it makes sense
* follow the same scheme when declaring variables
Re-indent file.
Remove unused code (`MakeAACInitData`).
Fix standalone filters compilation after 58df3305748f32017f7d72bda69388e13afbc9cd.
Don't add "Copy to clipboard" item if filters menu is empty.
MainFrm: Cosmetics for stats.

- Always show bitrate statistic in avg/cur style for consistency.
MainFrm: Cosmetics for timers.

- Move DVD timing related things to TIMER_STREAMPOSPOLLER for better
  reliability.
- Save current file position if it differs more than 30s than previous.
  In case when mpc-hc is not properly closed.
Fix possible freeze during DVD playback on XP after
f2b6ade8e8185fdc5908ed88df31e68a106786a9

Refs #4299
Do not try to set channel from WebServer thread.

Fixes #4415
Fix some signed/unsigned conversions that could lead to incorrect sign extension.

Fixes CID 1222029.
Lower the probability of buffer overflows when possible.

Convert to 64-bit integer before performing arithmetic operations on 64-bit builds.

Fixes CID 1222022 and 1222023.
Remember window position: Ensure the window can't be completely hidden after restoring it.

Restore the window at its latest position only it the window is at least partially visible on one enabled monitor.

Fixes #4408.