Add enhanced speed to m/s fields

Fix 1.fit from @OlafvdSpek

Prevent a division by zero error (#57)

* Prevent a division by zero error

* Updating divide by zero fix based on Adrian's suggestion.

* Remove trailing spaces

Merge pull request #55 from roznet/fix-64bits-coordinate

Fix 64bits coordinate

Update README.md

Update README.md

Update README.md

Merge pull request #38 from adriangibbons/dev

Some updates from FIT v2.2

handles string type appropriately

added gearChanges()