Allow additional comments in header checker.
Allow additional comments in header checker.

This enables us to include secondary attributions after the ImageJ
copyright notice, for use with code adapted from third party software.

This used to be revision r4332.

TehSAUCE/imagej,biovoxxel/imagej,biovoxxel/imagej,TehSAUCE/imagej,biovoxxel/imagej,TehSAUCE/imagej