add test for word token containing '=' without assignment

Reported in issue #10 our clever handling of '=' for assignments while
preserving the tokenization of words is not perfect.  This is not
unexpected and we'll work towards fixing these issues as the arise.
add test for equals inside string

Reported in issue #14.  Seems we're reporting equals from inside quoted
strings.
update word tokenization function

This new word tokenizer should fix issues #10 and #14.  It still has
some strangeness but seems to work for the cases we've found so far.
I'm sure more are lurking in the dark.