wc: more tests and fixes

My previous commits meant to bring our wc's output and behavior in line
with GNU's. There should be tests that check for these changes!

I found a stupid bug in my own changes, I was not adding 1 to the
indexes produced by .enumerate() when printing errors.

tests/fixtures/wc/alice in wonderland.txt

@@ -0,0 +1,5 @@
+Alice was beginning to get very tired of sitting by
+her sister on the bank, and of having nothing to do: once or twice
+she had peeped into the book her sister was reading, but it had no
+pictures or conversations in it, "and what is the use of a book,"
+thought Alice "without pictures or conversation?"