better intertalk between params and toolsheet

[suzannejin]

• add params diff_method cor_method enr_method
• the pipeline should be able to not only parse the info from the toolsheet, but also consider the above mentioned params
  • By default, if --pathway is not mentioned, the pipeline will run the methods as declared by these params. Hence, the pipeline should parse a ch_tools with those methods from the params.
  • When --pathway is mentioned, it will ignore those params and parse the methods as mentioned from the samplesheet into ch_tools