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
Remove unused module from verifyJP2s
Speed up initial file channel population

Makes file validity check the responsibility of the workers instead
of having to happen prior to starting any goroutines, allowing for
workers to begin work more quickly.
Allow parallelization

Not sure if this actually does anything - CPU usage is unchanged as far
as I can tell, and runtime speed doesn't seem to change any with or
without parallelization, even though the workers should be completely
independent other than the channel communications.
Require --tile-path when starting brikker
Add better logging of stream errors
Get JP2 file stats prior to response

Lets us display a 404 as well as provide a valid last-modified header
Add documentation for installation and use
Add variable log level to brikker
Merge branch 'feature/variable-logging'