prevent relatedTemplate from truncating a filename to end in "."

prevent relatedTemplate from truncating a filename to end in "."

Avoid a problem with temp file names ending in "." on certian filesystems
that have problems with such filenames.

relatedTemplate is quite an ugly hack really; since it doesn't know the max
filename length of the filesystem it can only assume that the filename is
max allowed length. When given the input "lh.aparc.DKTatlas.annot", it
wants to reserve 20 characters for tempfile so it truncates to "lh.". That
ending period is apparently a problem on some filesystem (FAT eats it, but
does not throw EINVAL; ntfs does not seem bothered by it, I don't know what
FUSE filesystem the bug reporter was really using).

Sponsored-by: Brett Eisenberg on Patreon