feat: dynamic target in TransitionClassification (#53)
* feat: add dynamic target #52
* test: fix check_target
* feat: add print format for Target
* test: fix Target
* feat: use Target in the inner working of Transition
* feat: add print format for Generic
* feat: check_target knows Target
* test: update TransitionClassifiication
* fix: Target did not accept NULL
* docs: update man
* docs: update news
* test: fix check_target test
* docs: export Target
* fix: checkmate::makeExpectation is missing
makeExpectation is imported to be used internally in our customised checkmate functions
* docs: fix wrong alias of Target
* test: fix Target tests
* docs: fix Target example
* docs: fix Target example in man
* Increment version number
* docs: update pkgdown
