Improved error messages in case of version incompatibilities. (#2657)
Clean makeobj
Fix check for objects
changing garbage collection in v8 extproc to happen much more rarely, avoids pathological cases
Propagate nestingDepth in MakeObject
Add an include in serialize_datum.cc.

This fixes an error I encountered when building on Mac OS X with clang in release mode. The error was that 'signbit()' was not defined. I don't know what other build scenarios this error might occur in.

This change has been reviewed by Daniel Mewes.
initial commit of #2623 v1.13.1 test fixes

This fixes all of the issues raised in the issue
ensure protobuf.test builds the right type of build
removing an extra log message
fix for D2992
Merge branch 'larkost/2623-v1.13.1-test-fixes' of https://github.com/rethinkdb/rethinkdb into larkost/2623-v1.13.1-test-fixes