

* mkvextract: SRT extraction: whitespaces will not be stripped from the start & end of the whole entry anymore.

* mkvmerge: SRT handling: whitespaces will now be stripped from the start & the end of each line of each entry, not just from the end of the last line. DTS in WAV but with a file name extension of `.dts` being detected as the wrong type of DTS. Prevents certain cases of mis-detection, e.g. Matroska, MP4, WAV…) will now preferred in the detection order over file types based on their extension.

* mkvmerge: file type detection: file types that can be detected unambiguously by their content (e.g. * mkvmerge: AVC/H.264 & HEVC/H.265 packetizers: when appending tracks the pixel dimensions will be checked & muxing will be aborted if they don't match. * all: Windows: UNC paths of type `?C:…` are supported again by switching back to Boost's file system library instead of using C++17's file system library. * mkvmerge: SRT handling: added a hack called `-engage keep_whitespaces_in_text_subtitles` which disables stripping whitespaces from the start & end of each line of SRT entries during muxing.
