use the YamlCPP from the system if already present and found by pkgconfig.  thanks @proglottis.
use msgpack 0.5.9 gem for ruby tests
fix a redefinition warning on yosemite
parse tinyint(n != 1) and mediumint mysql column definitions for completeness
remove unused Column member
hopefully fix intermittent failures due to stderr output from the snapshot import/export test
remove unused function
rename a function for clarity, is only used for error messages and shouldn't be used in SQL
extract and check default values on columns
bump protocol version, effectively changed by adding defaults
drop tables, columns, and keys if necessary to make the target schema match
implement adding and replacing keys to match the source schema