Change non-ascii characters to ascii

During builds, maven scrambles non-ascii characters, replacing them with
'???'. To avoid this problem, all non-ascii symbols have been replaced
with ascii characters. Only ascii characters should be used in the
future.
Update file headers

The migration of imglib2-ops to imagej-ops necessitated a change in
file headers to match the template of imagej-ops. This was achieved en
masse using maven build ‘license:update-file-headers'.
Add deprecated tag to imglib-ops

Instead of deleting the old imglib-ops after its migration, all files
have been marked with a deprecated tag. This way, the programs will
still function for users who rely on them while informing them that any
newer versions of the plugins can be found in imagej-ops.