Add Shorten (SHN) support (#1257)

* Add Shorten (SHN) support

* Add `<cmath>` include and use `std::log2`

* Use `uintptr_t` for buffer size calculations

* Work around `byteSwap` not using fixed width types

* Remove four-character codes

* Attempt to fix `static_assert`

* Revert previous commit

* Update `read_uint`* functions

* Use ByteVector for byte swaps

* Use different ByteVector ctor

* Rework variable-length input to use ByteVector

* Rename some variables

* Naming and formatting cleanup

* Add basic Shorten tests

* Rename a constant

* Rename `internalFileType` to `fileType`

* Add documentation on `fileType` meaning

* Add DO_NOT_DOCUMENT guard

* Fix shadowVariable issues reported by cppcheck

cppcheck --enable=all --inline-suppr \
  --suppress=noExplicitConstructor --suppress=unusedFunction \
  --suppress=missingIncludeSystem --project=compile_commands.json

* Formatting cleanup

* More explicit types

Reason for these changes: getRiceGolombCode(k, uInt32CodeSize) was
called with int k for uint32_t& argument.
There was also a warning from MSVC for line 299:
warning C4267: 'argument': conversion from 'size_t' to 'int'

* Additional explicit types

* Rename `SHN` namespace to `Shorten`

Also rename files to match

---------

Co-authored-by: Urs Fleisch <ufleisch@users.sourceforge.net>

bindings/c/CMakeLists.txt

@@ -25,6 +25,7 @@ include_directories(
   ${CMAKE_CURRENT_SOURCE_DIR}/../../taglib/ogg/opus
   ${CMAKE_CURRENT_SOURCE_DIR}/../../taglib/dsf
   ${CMAKE_CURRENT_SOURCE_DIR}/../../taglib/dsdiff
+  ${CMAKE_CURRENT_SOURCE_DIR}/../../taglib/shorten
 )
 
 set(tag_c_HDRS tag_c.h)

bindings/c/tag_c.cpp

@@ -55,6 +55,7 @@
 #include "opusfile.h"
 #include "dsffile.h"
 #include "dsdifffile.h"
+#include "shortenfile.h"
 #include "tag.h"
 #include "id3v2framefactory.h"
 
@@ -190,6 +191,9 @@ TagLib_File *taglib_file_new_type(const char *filename, TagLib_File_Type type)
   case TagLib_File_DSDIFF:
     file = new DSDIFF::File(filename);
     break;
+  case TagLib_File_SHORTEN:
+    file = new Shorten::File(filename);
+    break;
   default:
     break;
   }

bindings/c/tag_c.h

@@ -130,7 +130,8 @@ typedef enum {
   TagLib_File_XM,
   TagLib_File_Opus,
   TagLib_File_DSF,
-  TagLib_File_DSDIFF
+  TagLib_File_DSDIFF,
+  TagLib_File_SHORTEN
 } TagLib_File_Type;
 
 /*!