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.

Fix weeding of expansion candidates when recording Rearrange tests to check this, i.e. that there are changes in other files, not only the recorded one.