I searched for all usages of malloc, realloc, and calloc, and added NULL checks where they were missing.
"Signed" the contributors.txt file.
Merge pull request #98 from murrayju/outOfMemoryChecks

null checks for ?alloc calls; fix for #96
Include exception information for error 7 (reported for most IOException cases)
C# port: Fix CommonTreeNodeStream implementation of IPositionTrackingStream