Add missing error codes to `SheetMetalUnfolder.py`

[luzpaz]

There are certain places in the SheetMetalUnfolder.py that are missing error codes.

FreeCAD_SheetMetal/SheetMetalUnfolder.py

Lines 131 to 133 in 9bf7bac

	# TODO: Error Codes
	# - Put error numbers into the text
	# - Put user help into more texts

FreeCAD_SheetMetal/SheetMetalUnfolder.py

Lines 1859 to 1860 in 9bf7bac

	else:
	print('FIXME! make errorcondition')

FreeCAD_SheetMetal/SheetMetalUnfolder.py

Lines 1510 to 1513 in 9bf7bac

	if vert0Idx is None:
	#print 'catastrophy: ', fEdge.Vertexes[0].Point, ' ', fEdge.Vertexes[1].Point, ' ', eType
	Part.show(fEdge, 'catastrophyEdge')
	# FIXME, need proper failure mode.

FreeCAD_SheetMetal/SheetMetalUnfolder.py

Lines 783 to 785 in 9bf7bac

	if oppoPoint is None:
	print(' error need always an opposite point in a side face!')
	# FIXME: need a proper error condition.

[luzpaz]

Looks like @matthewdickinson's PR #10 was trying to address this

[luzpaz]

@shaise was this actually realized?

[shaise]

No, the PR was conflicting

[luzpaz]

Updated ticket with hyperlinked references in to the code

[alexneufeld]

@shaise This is probably not needed anymore, as we'll be using the new unfolder for the most part going forward

[shaise]

@luzpaz , Yes, with the new unfolder it is obsolete. Thanks for helping me tidy things up!