Adds an extra class (axis) to horizontal guides if the label is "0"
Adds an extra class (axis) to vertical guides if the label is "0". Fix #147

Commissioned by ClearSpark (http://www.clearspark.co.za)
Merge branch 'master' into classed_zero_axes
Merge pull request #147 from sirlark/classed_zero_axes

Adds an extra class (axis) to horizontal guides if the label is "0"