Release of final 2.0.0

We've just released version 2.0.0, which includes an updated core logic to handle all sources of errors separately, new default, high specificity settings for the somatic SNV caller, support for parallel calls even on single chromosome/sequence mappings and many tiny improvements and bug fixes. Note, we had to change the arguments names of the 'call' subcommand. The usage document has been updated to reflect this.