Baixar MKVToolNix 61.0.0 per a Windows

New features and enhancements
- all: IETF BCP 47/RFC 5646 language tags: implemented support for officially registered IANA language tag extensions.
- mkvmerge: track selection: when using language tags for selecting which tracks to keep, mkvmerge will now use component-based language tag matching instead of comparing them verbatim. This means that only those components (language, region etc.) the user specified will be required to exist and be equal. For example, if a file contains three subtitle tracks with languages es (generic Spanish), es-MX (Spanish as spoken in Mexico) and es-ES (Spanish as spoken in Spain), the user can use --stracks es to match all three tracks or be more specific with e.g. --stracks es-MX which would only match one track. Similarly inverting the selection with e.g. --stracks !es would get rid of all three tracks, not just the one for the generic Spanish.
- MKVToolNix GUI: multiplexer: deriving track languages from file names: the GUI can now detect full BCP 47/RFC 5646 language tags in file names. Part of the implementation of #3173.
- MKVToolNix GUI: multiplexer: deriving track languages from file names: the default list of boundary characters now includes -. Part of the implementation of #3173.
- MKVToolNix GUI: multiplexer: the GUI now defaults to the "lower" process priority setting for new installations in order to leave more room for other applications, especially interactive ones. Up to and including v59 the default was the "normal" process priority. v60 changed that to "lowest", which turned out to be much slower on Windows for no real gain over "lower". The setting will be auto-corrected by the GUI if the settings file were saved last with a version between v60.0.0.0 & v60.0.0.17 & "lowest" & it is still set to "lowest".
- HEVC dumper development tool: the tool has been renamed to xvc_dump and extended to be able to dump AVC/H.264 bitstreams, too. It now also detects the type of bitstream framing (ISO 14496-15 vs. ITU-T H.264/H.265 Annex B).

Bug fixes
- all: IETF BCP 47/RFC 5646 language tags: fixed a corner case of wrongfully allowing scripts/variants not listed in any of the entries in the prefix list when the prefix list contains prefixes restricting scripts/variants and a prefix solely with the language at the same time (example: the variant ekavsk with its prefixes sr, sr-Cyrl and sr-Latn where e.g. sr-ekavsk and sr-Cyrl-ekavsk should be allowed but not sr-Bali-ekavsk).
- mkvmerge: HEVC/H.265: the frame type of B frames was often wrongfully signalled as P frames instead, both with BlockGroup (missing second references) and SimpleBlock ("discardable" flag not set) elements.
- mkvmerge: SSA/ASS packetizer: the frame numbers will now be re-calculated when appending SSA/ASS tracks so that frame numbers of appended tracks are always strictly higher than frame numbers of the track they're appended to.
- mkvmerge, MKVToolNix GUI's chapter editor: BCP 47/RFC 5646 language tags: when BCP 47 language tags are used with a language code that isn't part of ISO 639-2, the programs will now write a legacy language element set to und ("undetermined") instead of not writing such an element at all or writing one with an invalid code. Fixes #3174.
- mkvmerge, MKVToolNix GUI's chapter editor: BCP 47/RFC 5646 language tags: the programs will ensure that the legacy and IETF language elements written will be unique within the scope of the same "chapter display" element.
- mkvinfo, MKVToolNix GUI's info tool: in summary mode the frame type was reported wrong for BlockGroup elements in which the ReferenceBlock elements were located behind the Block element.

Build system changes
- all: std::codecvt_utf8 is now used instead of Boost's utf8_codecvt_facet. The bundled copy the latter in lib/boost has therefore been removed.