a memory leak occurs when use "support type" option

due to following reasons

void generateSupportGrid(SupportStorage& storage, OptimizedModel* om, int supportAngle, bool supportEverywhere, int supportXYDistance, int supportZDistance)
{
	storage.generated = false;
	if (supportAngle < 0)
		return;
	storage.generated = true;

	storage.gridOffset.X = om->vMin.x;
	...
	storage.grid = new vector<SupportPoint>[storage.gridWidth * storage.gridHeight];
    ...
Merge pull request #48 from mspark93/patch-1

a memory leak occurs when use "support type" option