Replace token-templates dependency with gsub

Turns out gsub supports table-based substitution, which is all the
templating power we need here.
Remove token-template dependency in favor of gsub
Remove token templates
Add fold and map
Fix collection sorting using skim (not take)
Use map_table for list_in_order shallow copy

Avoids the song-and-dance of converting from table to stream to table.
Rename util to table_utils (and update requires)
Change file-utils to file_utils, update requires
Rename plugins to lettersmith_ per convention