- update to 1.7.0:
* A C++14 compliant C++ compiler is now required.
* libEBML v1.4.3 is now required.
* Remove Coremake project files
* Add `KaxInternalBlock::GetRelativeTimestamp()` to access unscaled
block timestamps.
* Fixed problems with the generated `pkg-config` files if any of the
installation paths are absolute.
* Added several enums in `namespace libmatroska` for the various
elements that are constrained to a set of options:
`MatroskaTrackType`, `MatroskaTrackEncodingCompAlgo`,
`MatroskaChapterTranslateCodec`, `MatroskaTrackTranslateCodec`,
`MatroskaVideoFlagInterlaced`, `MatroskaVideoFieldOrder`,
`MatroskaVideoStereoMode`, `MatroskaVideoAlphaMode`,
`MatroskaVideoOldStereoMode`, `MatroskaVideoDisplayUnit`,
`MatroskaVideoAspectRatioType`, `MatroskaVideoMatrixCoefficients`,
`MatroskaColourChromaSitingHorz`, `MatroskaColourChromaSitingVert`,
`MatroskaVideoRange`, `MatroskaVideoTransferCharacteristics`,
`MatroskaVideoPrimaries`, `MatroskaVideoProjectionType`,
`MatroskaAudioEmphasis`, `MatroskaTrackPlaneType`,
`MatroskaContentEncodingScope`, `MatroskaContentEncodingType`,
`MatroskaContentEncodingAlgo`, `MatroskaAESSettingsCipherMode`,
`MatroskaContentSignatureAlgo`, `MatroskaContentSigHashAlgo`,
`MatroskaChapterSkipType`, `MatroskaChapterProcessTime` and
`MatroskaTargetTypeValue`.
* Updated the semantics to the latest specifications, deprecating the
following elements by preventing code to write them:
`KaxClusterSilentTracks`, `KaxClusterSilentTrackNumber`,
`KaxSlices`, `KaxReferenceFrame`, `KaxReferenceOffset`,
`KaxReferenceTimeCode`, `KaxTrackTimecodeScale`,