Improving the Error handling

[tesonep]

• Better handling exceptions in the events and in the defer actions.
• Fixing the universe
• Adding tests

[tinchodias]

This may close #396 and #406

[tinchodias]

Reminder: Need to check what happens with an animation that signals an error on each pulse

[tinchodias]

Should have fixed #421 too

[tinchodias]

This demo with a repeated task with error + a ok repeated task shows that the space tolerates it. The one with error stops its repetition:

s := BlSpace new.
s extent: 100 asPoint.
s show.
s root enqueueTask: (BlRepeatedTaskAction new
	delay: 1 second;
	action: [ self inform: 'bonjour' ]).
s root enqueueTask: (BlRepeatedTaskAction new
	delay: 1 second;
	action: [ 1/0 ])

[tinchodias]

Still this should be fixed:

testOpeningAnSpaceDeferingAnErrorKeepsLoopRunning

	| aSpace logger |

	UIManager default class = MorphicUIManager 
		ifFalse: [ ^ self skip ].

	hostClass = BlOSWindowSDL2Host 
		ifFalse: [ ^ self skip ].
...