Some bugs and other small things.

[TomSnijders]

Description

Functionality

• print.sienaGroup now also specifies the node sets for covariates
  and restricts printed line lengths to 64.
• Use of r in estimate_onestep effectuated.
• checkEffects.R corrected so that it will run without errors
  and can be used for batch checking (will take a long time).

Bug correction

• make_specification corrected for a continuous dependent behavior variable
  and for two dependent networks and varying actor covariates (effects.r).
• Use of prevAns with one-step estimator corrected (initializeFRAN.r).

Checklist:

Checks

• If possible, I have added tests that prove my fix is effective or that my feature works
• The package builds on my OS without issues
• My changes generate no new warnings

Documentation

• I have added a description of all changes to this pull request above and to the NEWS.md file
• I have bumped the version in the DESCRIPTION and man/RSiena-package.md files by the appropriate increment:
  • 'major' (incompatible API changes)
  • 'minor' (add functionality in a backwards compatible manner)
  • 'patch' (backwards compatible bug fixes)