Move openjpeg into its own package
Extract C code from Go file
Move openjpeg logging into Go
Add log level controls

This should use a real logging system, but for now I'm just trying to
make an easy way to skip logs for the verification code
Move other logging to use internal logger

Adds go logger for internal logging, which GoLog calls after converting
C types to Go types.  This allows trapping of all logging (C and Go)
via LogLevel setting
Add JP2 verification command