stop using Data::Walk

[i110]

Data::Walk overwrites $_ global variable without any rewind, and it occasionally causes unexpected behavior (I met very hard bug due to that) In my humble opinion Data::Walk is poor-quality, and the traversal logic is simple enough to write in scratch.

[i110]

I'm sorry I missed the fact that Data::Walk has already addressed that issue starting from 2.0 (released on this spring) close shimasu

[i110]

いずれにせよ Data::Walk はアレなので公益のためreopened