enforce subn method via boolean switch
There are only 2 patterns to choose, and so far only 1 case
where kwtemplater.re_kw.subn is applied on data read from
the working directory: when recording added files.
With this change the code reflects more closely the boolean
character of the switch and underlines the special case.
syntax: glob
*.pyc
*.pyo
*~
*.swp
*.orig
*.rej
.DS_Store
build/*
MANIFEST