Make the Smalltalk generator use non-hardcoded namespaces.

Make the Smalltalk generator use non-hardcoded namespaces.

- Make the Smalltalk generator use program->get_namespace("smalltalk.*")
  instead of program->get_smalltalk_{category|prefix}()
- Eliminate the explicit "smalltalk_{category|prefix}" in t_program.
- Deprecate the smalltalk_{category|prefix} tokens.
- Update example .thrift files and syntax files.

This was a little more complex than the others.  We now convert "." to "-"
in Smalltalk categories, because we no longer lex them as tok_st_identifier.

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@665601 13f79535-47bb-0310-9956-ffa450edef68