Added pendingchanges for accessor changes

Signed-off-by: Nick Avramoussis <4256455+Idclip@users.noreply.github.com>

Author: Idclip

pendingchanges/value_accessor.txt

@@ -0,0 +1,14 @@
+API changes:
+- Significant infrastructural change to the ValueAccessor header and 
+implementation. All ValueAccessor specializations have been consolidated
+into a single class which support all possible ValueAccessor configurations
+using index_sequences. Backwards compatible declarations have been provided.
+The new ValueAccessor implementation is marked as final.
+
+Improvements:
+- Introduced openvdb::make_index_sequence to solve clang compilations
+issues with compiler builtin index_sequence implementations.
+- Introduced openvdb::TupleList to wrap std::tuple and provide interface
+interop methods with openvdb::TypeList.
+- Added OPENVDB_FORCE_INLINE, OPENVDB_LIKELY and OPENVDB_UNLIKELY macros.
+