Describing the new features in SAPIC+

[rkunnema]

We revised the following Sections:

• Model Specification using Processes (new syntactical elements, refs to papers)
• Predicates (minor details)

We added new Sections:

• description about export to ProVerif and Deepsec
• new tool tamarin-troop.py (Thanks @niklasmedinger!)

Extra stuff:

• Removed warnings in Makefile and errors related to new pandoc versions.

[jdreier]

There seem to be several todos left in the files?

[rkunnema]

Thanks, I've removed those. :)

[cascremers]

Hmm, shouldn't this be a PR for the develop branch of the manual?

[rkunnema]

@cascremers absolutely, thanks!