Axis Tick Marks

[noelwelsh]

Add support for displaying tick marks.

Properties include:

• Major tick mark extent. The amount in and out that the major tick marks extend relative to the axis. (In = towards the data, out = away from the data)
• Minor tick mark extent. As above for minor minor tick marks
• Colour
• Font
• Label location. This is where the label for a tick mark is located relative to the tick mark. This might be difficult. Can maybe use Doodle Landmark to express.
• Label formatting. A Double => String function? Might be difficult.
• Layout: automatic or manual. Automatic means an algorithm chooses where the major and minor tick marks are. Manual means the user specifies.