Configuration parameter copy and modify functions extended

[Dr15Jones]

The clone and Modifier.toModify methods have been extended to allow further modifications to the parameters after they have been copied.

1. Specify None as the value of the parameter will cause the parameter to be removed from the configuration
2. Parameters within embedded PSets can now be modified using a python dict as the value. The keys of the dictionary are the parameter
   names and the values are the new values to use.
   The clone and Modifier.toModify both call the same helper function to do the work of modifying the copied parameters.

This also fixed the problem with the previous pull request for this feature.

[cmsbuild]

A new Pull Request was created by @Dr15Jones (Chris Jones) for CMSSW_8_0_X.

It involves the following packages:

FWCore/ParameterSet

@cmsbuild, @smuzaffar, @Dr15Jones, @davidlange6 can you please review it and eventually sign? Thanks.
@Martin-Grunewald, @wddgit, @wmtan this is something you requested to watch as well.
@slava77, @Degano, @smuzaffar you are the release manager for this.

cms-bot commands are list here #13028

[Dr15Jones]

I tested this with #13216 by running runTheMatrix.py -l 5.1,140.1 where those two workflows exhibited the two different failures seen in the IB. With this pull request the jobs ran fine.

[Dr15Jones]

please test

[Dr15Jones]

+1

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/11133/console

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_8_0_X IBs after it passes the integration tests. This pull request requires discussion in the ORP meeting before it's merged. @slava77, @davidlange6, @Degano, @smuzaffar

[Dr15Jones]

The test aborted because it timed out

[makortel]

@Dr15Jones It looks like PSet.clone() does not work with dict arguments. Example (tested in CMSSW_8_1_X_2016-02-22-1100):

$ cat foo.py
import FWCore.ParameterSet.Config as cms
p1 = cms.PSet(anInt = cms.int32(1), a = cms.PSet(b = cms.int32(1)))
p2 = p1.clone(a = dict(b = 2))
print p2.a.b.value()
$ python foo.py
Traceback (most recent call last):
  File "foo.py", line 3, in <module>
    p2 = p1.clone(a = dict(b = 2))
  File .../CMSSW_8_1_X_2016-02-22-1100/python/FWCore/ParameterSet/Types.py", line 653, in clone
    myparams[key].setValue(value)
AttributeError: 'PSet' object has no attribute 'setValue'

[Dr15Jones]

#13526