Fix: Take into account that new versions of Tesseract uses the file extension .hocr instead of .html

Signed-off-by: Jerome Flesch <jflesch@gmail.com>
Fix: Make hocr parsing more resistant: there maybe extra data around the box positions

Signed-off-by: Jerome Flesch <jflesch@gmail.com>
Merge branch 'master' of github.com:jflesch/pyocr

Conflicts:
	src/pyocr/tesseract.py

Signed-off-by: Jerome Flesch <jflesch@gmail.com>