The only remaining 'py.test' references are:
* those referring to the 'py.test' executable
* those in code explicitly testing py.test/pytest module compatibility
* those in old CHANGES documentation
* those in documentation generated based on external data
* those in seemingly unfinished & unmaintained Japanese documentation
Minor stylistic changes and typo corrections made to documentation next to
several applied py.test --> pytest content changes.
On python2.x text arguments where passed through str, which meant only
ascii-encodable strings could be used. This uses
py.builting._totext() to keep unicode until it is written out to the
file, which was already UTF-8 encoded.