Merge pull request #4 from icaughley/master

A couple of Postgres changes.
Rename the characteristic_type method to characteristic_type_key to more accurately reflect the intention
Merge branch 'master' of github.com:realityforge/domgen
Define various characteristic types
Ensure that symbols for child config elements are correctly escaped
Remove support for explicitly setting the java type
Explicitly invoke the correct error method to avoid invoking the one included with builder
Fix spelling
Ensure that all the config elements are expanded on instances prior to freezing the types
Initial attempt at reworking the mechanisms for defining characteristic types
Correct the date types
Continue converting across java style characteristics
Explicitly call the error functions
Whitespace
Avoid hardcoding and reuse existing configurations
Move remaining method to singleton class
Remove unused characteristic types
Simplify the way packages are defined
Whitespace
Generate an error if primitive_java_type is incorrectly invoked