NEAREST - NEAREST edge or vertex in triangulated model

nearestEdgeInModel	Return pointer to edge in model nearest to
                    	specified (x,y) coordinates

nearestVertexInModel	Return pointer to vertex in model nearest
                   	to specified (x,y) coordinates

Function Prototypes:
Vertex* nearestVertexInModel (Model *m, Vertex *start, float x, float y);
Edge* nearestEdgeInModel (Model *m, Edge *start, float x, float y);

nearestEdgeInModel:
Input:
m		model
start		edge to look at first (NULL to begin looking anywhere)
x		x-coordinate
y		y-coordinate

Returns: pointer to nearest Edge

nearestVertexInModel:
Input:
m		model
start		vertex to look at first (NULL to begin looking anywhere)
x		x-coordinate
y		y-coordinate

Returns: pointer to nearest Vertex

Author:  Dave Hale, Colorado School of Mines, Fall 1990