Strip \x{c2} from .txt files and audit.

Strip \x{c2} from .txt files and audit.

Am unable to keep the build process from inserting spurious \x{c2}
characters into the created .txt files.

Strip the characters in Tidytxt.

Add SanityTestText to do a final audit for non-ASCII characters in the
.txt files.  Dependency: pcregrep if available, else uses Perl.