This patch completes memory management for the C implementation.
- All schema and datum objects are now freed when dereferenced
- Four new methods have been added avro_wrapstring, avro_wrapbytes, avro_givestring, and avro_givebytes. These new methods allow C developers to explicitly state if they want libavro to copy bytes/string (the default), "wrap" them with no memory management or "give" them to libavro to manage. This allows for less buffer copying when decoding data.
- Issues with type punning have been resolved to prevent compiler warnings
- The map and record data structures now implement management correctly.
- A new valgrind test is added and runs during make check if valgrind is found on the build system.
A future optimization will be to have a stack of allocated objects for each obj type instead of always using malloc() and free().