Typos/speling and English

Fixed some typos/speling, and replaced the word "composant" by its English counterpart "component".
More typo/speling, English

Includes rather a rewrite about the line about test coverage.
Even more typo/speling, English

design -> is designed to
Merge pull request #7 from gforcada/fix-tests

fix for issue #2
Merge pull request #3 from khink/master

readme improvements
Misc. spell fixes and rst formattings