Fix: Possible double free when resetting PGS subtitles.

This resulted in random crashes when seeking quickly in a file with PGS subtitles and other various cases.

Fixes #4240.
Update translations from Transifex:

 - Catalan
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Fixes #4268.
Don't prevent the users from using the ISR if they choose not to block VSFilter like filters.

This commit fixes ticket #4231.
PGS subtitles: Enqueue empty segments to be sure subtitles are properly cleared when using the queue.

This is a work-around and will be improved later.

Refs: #3691.
Update translations from Transifex:

 - Croatian
 - Dutch
 - German
 - Japanese
 - Spanish
 - Ukrainian
 - Vietnamese
Update files for v1.7.5 release.
Update docs/Release.txt.
Set MPC_NIGHTLY_RELEASE to 1.
Readme.md: switch to SVG badge.
VSFilter/ISR: Fix override placement not being applied even if enabled.

ISR: Fix subtitle default style being lost after changing default style in settings.

Fixes #34.
VSFilter: Pass through dwTypeSpecificFlags and dwInterlaceFlags.

This fixes interlaced videos.

Fixes #2671
Repaint video frame when toggling statistic.
Hide unneeded line in statistic when VSync is enabled.
RTS: Fix outline size when using default style for ASS subtitles.

Fixes #3701
RTS: Add some rounding to ensure higher precision.
RTS: Preserve proper subtitle positioning and constant font size for default style override along different subtitle files.

Fixes #1574
RTS: Don't remove subtitles effect when default style is applied.

"Default Style" option is to apply default style for subtitles and not
actually completely break them.

Fixes #4171
ISR: Don't set subtitle again when manipulating style.

Fixes #2244
ISR: Disable "Default Style" menu item when not applicable.
Set the execute permissions on batch files.

Command used to prepare this patch
`git ls-files -z '*.bat' | xargs -0 git update-index --chmod=+x`