remove "manual" directory from the repo & tarball?

[slayoo]

Migrated from: https://sourceforge.net/p/blitz/bugs/56/

As mentioned in blitz/manual/README (Sep. 2004): "...files that were previously contained in this directory have been replaced by the .texi files in the doc subdirectory and are now obsolete"

The examples subdirectory is now both in manual and doc, and the contents differ.