RegisterHotkeys: Fix a rare crash.

Use the Windows API more correctly and add more error checking.

This commit fixes #2971.
Move code of shaders from registry and ini to separate files in folder.
Revert "Move code of shaders from registry and ini to separate files in folder."

This reverts commit da59b57a76da243275345bc5e6045382e13102e8.
Update mpc-hc_setup.iss.

* simplify a preprocessor check
* rename a function
* use a wildcard for the translation dlls
* reindent
installer: remove unneeded strings from Inno Setup's language files
custom_messages.iss: update copyright year
checkyear.sh: add .iss files in the files to check
Updated Swedish translation.
Fix: Prevent the volume OSD message from erasing the filename on startup.

This commit fixes #2985.