SPECTUB: write warning if image radius is larger than detector radius

[KrisThielemans]

Fixes #567

[KrisThielemans]

@mastergari potentially there's a similar warning that could be written for the pinhole code, but I didn't immediately see where. In any case, it is not vitally important.

[mastergari]

@KrisThielemans the pinhole-SPECT code checks if a voxel is located behind or within a pinhole. These are checked when looping over the holes during weight matrix calculation.

STIR/src/recon_buildblock/PinholeSPECTUB_Weight3d.cxx

Line 1109 in ff1c20b

case 88: error( "\n\nError weight3d: Voxel located behind or within the hole.\nRevise volume settings or use cyl mask.\n" ); break;

STIR/src/recon_buildblock/PinholeSPECTUB_Weight3d.cxx

Lines 352 to 361 in ff1c20b

	bool check_xang_par( voxel_type * v, hole_type * h ){
	bool ans = true;
	//...vector voxel-hole, angles and distances...............................
	float ux1 = h->x1 - v->x1 ;
	float uy1 = h->y1 - v->y1 ;
	if ( uy1 <= EPSILON ) error_weight3d ( 88, "" );

STIR/src/recon_buildblock/PinholeSPECTUB_Weight3d.cxx

Lines 391 to 400 in ff1c20b

	void voxel_projection_mph ( lor_type * l, voxel_type * v, hole_type * h, wmh_mph_type &wmh )
	{
	//...vector voxel-hole, angles and distances...............................
	float ux1 = h->x1 - v->x1 ;
	float uy1 = h->y1 - v->y1 ;
	float uz1 = h->z1 - v->z ;
	if ( uy1 <= EPSILON ) error_weight3d(88, "" );