hub.darcs.net :: darcs -> darcs-screened -> changes

Using show results in escaping all non-ASCII characters, which can distorts patch comments. Instead, by using simple quotation, we can fully comply with the DOT language escaping and encoding rules: > In quoted strings in DOT, the only escaped character is > double-quote ". That is, in quoted strings, the dyad \" is > converted to "; all other characters are left unchanged. See https://www.graphviz.org/doc/info/lang.html.

This is needed to debug problems like issue2739.

This introduces the concepts (definitions) of positive/negative dependency and similarly for conflict. The invariants and proofs are now based on these notions. The proofs remain informal but should now be mathematically exact, i.e. formalizable in principle.

The few use cases are easily replaced with the less problematic 'prefix'.

This internal procedure is called in just one place.

This is so that when we show failing test cases we cannot run into encoding errors. Note that shell tests are not affected by this since they are run with DARCS_DONT_ESCAPE_ANYTHING which takes precedence.

It doesn't quite behave as one might expect from the name.

This is a slightly more high-level function.

(Prop1.tShowRead unsafeCompare) is the same as PropG.showRead

This is a pure refactor to make it easier to change the type of the commandPrereq member of DarcsCommand.