Fix Lepiter pages not being movable

[onierstrasz]

When Lepiter pages contain snippets that are not text or code, the page can no longer be moved to another database. (The database button at the bottom left is greyed out.) This is because the page is assumed to contain snippets that are “attached” to the database. For example, a picture snippet may be attached to a picture file in a specific database. However the current logic, defined in LePage>>#canMoveToAnotherDatabase, is too restrictive. It should be refactored so that each snippet is explicitly asked if it contains attached links.

LePage>>#canMoveToAnotherDatabase
	(self outgoingExplicitLinks anySatisfy: [ :aLink | aLink isAttachedLink ])
		ifTrue: [ ^ false ].
	(self incomingLinks anySatisfy: [ :aLink | aLink isAttachedLink ])
		ifTrue: [ ^ false ].
	self
		allChildrenBreadthFirstDo: [ :aSnippet | 
			(aSnippet isTextSnippet not and: [ aSnippet isCodeSnippet not ])
				ifTrue: [ ^ false ].
			(aSnippet incomingLinks anySatisfy: [ :aLink | aLink isAttachedLink ])
				ifTrue: [ ^ false ].
			(aSnippet outgoingExplicitLinks anySatisfy: [ :aLink | aLink isAttachedLink ])
				ifTrue: [ ^ false ] ].
	^ true

Better yet, we should add logic to move snippets containing attached links, but this could be for a later enhancement.

[onierstrasz]

The refactored method now looks like this:

canMoveToAnotherDatabase
	(self outgoingExplicitLinks anySatisfy: [ :aLink | aLink isAttachedLink ])
		ifTrue: [ ^ false ].
	(self incomingLinks anySatisfy: [ :aLink | aLink isAttachedLink ])
		ifTrue: [ ^ false ].
	self
		allChildrenBreadthFirstDo: [ :aSnippet | aSnippet hasAttachedLinks ifTrue: [ ^ false ] ].

And LeTextualSnippet>>#hasAttachedLinks looks like this:

hasAttachedLinks
	(self incomingLinks anySatisfy: [ :aLink | aLink isAttachedLink ])
		ifTrue: [ ^ true ].
	(self outgoingExplicitLinks anySatisfy: [ :aLink | aLink isAttachedLink ])
		ifTrue: [ ^ true ].
	^ false

But which other snippet classes should override hasAttachedLinks to false or something else?