[PATCH 0 of 4] keyword: fix weeding of expansion candidates when recording

[Christian Ebert]

Hi,

1st patch fixes an oversight on my part: when recording
candidates must be a subset of repo['.'].files() not just
repo['.']. The bug caused all recorded files to be overwritten,
not only the changed ones.

The tests have been rearranged to prevent this from happening
again.

3rd patch changes the optional argument of kwtemplater.overwrite()
to a boolean, reflecting the nature of the switch.

2nd and 4th patch are hopefully self-explanatory tweaks.

c