In the case of a failure in the initialization of one output_processor the
remaining `initialize` methods may not get called causing variables to
not be initialized correctly.
Expose the context to the initialize and finalize functions for Output
Processors. This was found to be necessary for the upcoming PostgreSQL
Output Processor.
- Add copyright headers to files that did not already have them
- Update the year to the last year the file was modified in files with
existing headers.
