Fix typos in comments

Using https://github.com/lucasdemarchi/codespell and excluding:
examples/animator.js
examples/georss.xml
examples/kml/sundials.kml
examples/utfgrid/geography-class/2/1/1.grid.json
lib/OpenLayers/Format/GeoRSS.js
lib/OpenLayers/Lang/*
tests/*
tools/BeautifulSoup.py