Update CHANGELOG with hash table update
- Add casts to aid clean C++ builds (#47)
- Add missing const specifier in generated `buffer_start` methods - removes C++
warnings (#48)
-- Update external/hash, fix bugs in sorted robin hood hash - no impact on
- flatcc.
+- Update external/hash, remove buggy Sorted Robin Hash that wasn't
+ faster anyway - no impact on flatcc.
## [0.4.2]
- Fix SIGNIFICANT bug miscalculating the number of builder frames in
