MTK fault calculator: create "simple" fault geometry class

[Graeme Weatherill]

The purpose of this bug is to define and create a simple fault geometry class.

A simple fault geometry is defined by:
1) Trace - a set of points (at least two), where each point is defined using a Long., Lat.
2) Upper depth - the depth of the shallowest edge of the fault (km)
3) Lower depth - the depth of the deepest edge of the fault (km)
4) Dip - the angle (in degrees) between the fault and the horizontal plane

A simple fault will allow to compute: length, width and area.

The length is calculated by summing the distances between successive points along the trace.
The width is calculated by: width = (lower_depth - upper_depth) / sin(dip)
The area = length * width

Constraints on the input data:
1) Trace: Longitude (-180. to 180., float), Latitude (-90. to 90., float)
2) Upper Depth - Positive float
3) Lower Depth - Positive float greater than or equal to upper depth
4) Dip: 0. to 90. (float)