integrate CASL consistency checker with Hets

[till]

integrate CASL consistency checker with Hets, that is, check which ideas of the CCC are not implemented in Hets yet and realize them in Hets. See http://www.informatik.uni-bremen.de/cofi/ccc/

• define consistent CASL as a language for CASL models. Essentially Fig. 3 "special extensions", LNCS 2267, p. 314
• dependency spilt: A CASL basic spec (resp., the corresponding development graph node) can be split into a series of extensions, such that each individual extension is freely permutable
• for each basic item, generate
  • proof obligations (e.g. for subsorts)
  • conservative extension (model in cons. CASL)
  • remaining things that must be handeled differently Collect these things into three new basic specs/extensions

For an example, see the attached image.

A first version will add a development graph menu, later on, the tactic language should be extended.

Related tickets (for the structured level): #18 and #149.

As a first step, try out the example from the attached image with the current tool. Perhaps a simpler concepts can be used.